Grey Literature

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Most library users think of reference sources, books, and periodicals as their main "go to" information sources for library research. However, many important research findings are published first and only as technical notes, conference proceedings, electronic communications, projects reports, and other lesser-known works. Traditional finding aids may not be effective in locating and accessing these materials. These types of documents are known as "grey literature" or "gray literature".

Although Google is getting better at identifying grey documents, these information sources continue to be part of the "hidden web" or "deep web". In other words, they're not easy to find. They often lie deep inside web servers without metadata or other descriptions important for identification by web crawlers.


Grey Literature Defined

studentGrey literature includes materials not formally published through traditional commercial publishing channels. Many of these works are found on websites. According to (Reitz, 2014), grey or gray literature is

"documentary material in print and electronic formats, such as reports, preprints, internal documents (memoranda, newsletters, market surveys, etc.), theses and dissertations, conference proceedings, technical specifications and standards, trade literature, etc., not readily available through regular market channels because it was never commercially published/listed or was not widely distributed. Such works pose challenges to libraries in identification (indexing is often limited) and acquisition (availability may be uncertain). Absence of editorial control also raises questions of authenticity and reliability. Alternative methods of supply and bibliographic control have evolved in response to the need to preserve and provide access to such material."

According to Farace and Schopfel (2010), the term grey literature generally includes three types of documents: conference proceedings, reports, and doctoral theses. The definition usually limits grey literature to those documents that lack “commercial control”. In other words, they aren’t published through traditional publishing houses in books or journals. Commercial literature is sometimes referred to as “white literature”.

Unpublished manuscripts, newsletters, patents, technical notes, field notes, product catalogs, presentation materials, correspondence, laboratory notes, and data sets may also be included under the umbrella of grey literature. Farace and Schopfel (2010) note that these documents can contain “unique and significant” information that isn’t published elsewhere.

Institutions of higher education are major producers of grey literature. From online course materials to dissertations, universities churn out endless content across disciplines.

Read Schopfel, Joachim & Farace, Dominic, J. (2009). Grey literature. Encyclopedia of Library and Information Sciences, 3rd Edition. Taylor and Francis.

GreyNet is "dedicated to research, publication, open access, and education in the field of grey literature. This website is useful for collecting background information about this topic.

Pros and Cons of Grey Literature

grey litGrey literature can provide useful information on a topic. Because it doesn't go through traditional publication channels, it can be shared very quickly. Grey literature often summarizes and communicates ideas in ways that are different from other documents. Many of the documents are concise, so these sources can convey complex information in simple terms, quickly. Many companies and agencies produce grey literature such as brochures and pamphlets for public distribution, so these works are a good gauge of public interests.

Besides the ability to identify additional information on a topic, grey literature provides the opportunity to locate materials with alternative perspectives and lesser known specializations. These types of information sources can also be used to battle against publication bias. In other words, publishers tend to select high-impact studies with positive results for publication. This means that many excellent studies go unnoticed by the mainstream. Non-traditional publishing outlets provide an opportunity for this research to be read.

girls working

On the other hand, it's important to remember that many pieces of grey literature have not been peer reviewed. As such, it's essential that scholars carefully review the sources themselves. In addition, it can be difficult to locate studies of interest. Unlike subscription databases that provide well-indexed materials, some open access tools have limited search capabilities.

According to AcademyHealth (2006),

"grey literature has long-term value, particularly because it provides policy context and implications that may not be found in the published literature. In fact, advisory committee members believed that the value of grey literature is on par with that of traditional published literature. Relevancy, progress, and how debate changes over time on a particular topic can be assessed from these materials. Another use of grey literature is to establish historical documentation. The progress of a document to its finished form can sometimes be as valuable as the finished product, and the various drafts of a document can fill in gaps in the historical record."

Access to Grey Literature

Interest in grey literature has gone hand-in-hand with the recent open access movement. Many librarians and subject matter researchers began to realize that a huge untapped resource needed to be made widely available. Rather than going to publishers, many librarians and scholars worked together to develop their own databases and institutional repositories to house these important data collections. The government has also gotten on board to promote open access to documents.

In the past, it was often difficult to access dissertations, theses, reports, and other types of print materials. However, universities, government agencies, and other organizations are increasingly digitizing these materials and making them available online. The search is on for more documents that can be shared.


Look for grey literature in the following locations:

try itTry It!
Go on a grey literature scavenger hunt. Select a topic and search the major databases services such as EBSCO, Gale, and ProQuest seeking out documents. Next, visit an organizational website related to your topic. Look for reports, proceedings, or other types of grey documents.

The Document Types in Grey Literature page at GreyNet contains a list of many different types of grey literature. These categories along with additional document types are listed below.

Let's explore the many types of documents in the category of grey literatures.

Conference Documents

From conference papers and posters to conference programs and proceedings, products of conferences are an important source of information for researchers. They often contain the latest information on a topic and may be the only place that an unpublished work can be located. Conference documents are often available through conference websites and are archived from year-to-year by the sponsoring organization. In some cases, the proceedings are only available to those that attended the conference.

Do a search in ProQuest for conference proceedings and papers.

PapersFirst via FirstSearch is available through WorldCat. You can search both PapersFirst and Proceedings using the Databases option.

annetteLamb's Personal Connection
In many subject areas, library users will want the most up-to-date information. Conferences are one of the best sources for information.

Go to an organization's website and look for their latest conference. The website will often note where the papers can be located. Many times organization websites archive these materials themselves and they may not be available anywhere else.

If you aren't able to locate the most recent conference proceedings, there are other ways to connect with new content. Scan through online conference programs for the names of key researchers. Then, search for recent articles by those people. You may also be able to locate articles at pre-print websites.

Course Materials

From syllabi and calendars to course guides and tutorials, many course materials are not formally published. Many of these materials reside on university web-servers. While some are behind firewalls, others are open access. Use of content management systems such as Blackboard and Canvas has increased online availability of course materials.

Some universities such as MIT have embraced the open courseware concept.

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Go to MIT Open Courseware. Search for a course in your discipline area using the Course Finder. Notice that many of the syllabi include resource lists. These can be valuable sources of information.

Data Sets and Statistics

From voting patterns to animal populations, statistical information is critical across disciplines. Keep in mind that most scholars will want the original source of data rather than a source that simply converted the data into a chart or graphic. Statistical sources provide rankings, ratings, and raw data on a wide range of topics.

Regardless of your discipline, it’s important to be familiar with key concepts related to data and statistics.

Data and Statistics Defined

Data and statistics are different.

Julia Bauder (2014, 3) states that data

"is raw input for some sort of statistical analysis. A list of all of the traffic accidents in New Jersey in 2010, with information about the drivers (e.g., age, blood alcohol content, whether they were using a cell phone at the time of the accident) and the accident (e.g., time of day, weather, number of cars involved) would be data."

Bauder also (2014, 3) states that statistics

"are the results of a statistical analysis of the data. Statistical analysis does not have to mean some sort of complicated multivariate regression. In many cases, it is simply an average, a percentage, or a frequency. For example, the percentage of accidents that occur during snowstorms, or the frequency of accidents involving teenage drivers, are examples of statistics that could be generated from this data."

brainFinally, Bauder notes that "certain pieces of information can be treated as either statistics or data, depending on what the user wants to do with that information." For instance, you might use a statistic such as the unemployment rate in a research paper. However, this single number could be joined with other numbers for an analysis of changing unemployment rates. In this case, that single number would be treated as a data point (Bauder, 2014).

Rather than studying the entire population, researchers often collect data from a sample that represents the larger population. Sampling is based on the idea that you can make generalizations from a representative group.

Descriptive statistics involve the use of numerical and graphical representations of data to seek out patterns and draw conclusions. Inferential statistics use sample data to make predictions about larger sets of data.

In many cases data is used to forecast, project, or estimate. In other words, data is used to predict what might happen in the future. Keep in mind that many factors such as technological advances or natural disasters can interfere with projections.

A data set is a collection of data. This data may be presented on a single table or matrix. However, it may also be contained in a large database and displayed in various forms. Examples include:

According to Bauder (2014, 4), microdata is

"used to refer specifically to the kind of data that is, unequivocally, data rather than statistics: raw observations, survey responses, and the like that are not the product of any kind of statistical analysis or summary."

According to Bauder (2014, 4), aggregate data is

"data produced by some sort of statistical procedure, such as averaging or, in the most basic and perhaps the most common example, simply adding up the number of cases. Monthly unemployment rates are an example of what might be referred to as aggregate data".

Data and Statistics in the Library

Today's Internet allows users to quickly download large amounts of information. In addition, tools like Microsoft Excel allow anyone make use of this information. Kellam and Peter (2011) have found that there's increasing interest in quantitative information. Users without a background in statistics can search data sets that provide an easy-to-use interface such as American Factfinder. However complex data set that don't provide an interface can be useless without specific software and analysis skills. Kellam and Peter (2011, 15-17) state:

Librarians working with data need to think about what's possible and practical with information seekers.

"Aggregate statistical sources can be a gateway into more complex data for novice users; librarians need to be aware of and learn how to support these basic numeric products with skill. Librarians can encourage interest in using numeric information during the early stages of student research. For example, we should encourage lower-level students to use sources like American Factfinder" (Kellam & Peter, 2011, 19).

Most university faculty have access to software such as SAS or SPSS. However for library users without these tools, open source alternative such as The R Project can be useful for statistical computing and graphics.

General Sources of Data and Statistics

Gathering data and statistics is a time-consuming and often expensive process. Governments around the world collect public data as well as global organizations such as the United Nations. In addition, private data is gathered by businesses, nonprofits, and other types of organizations for a variety of purposes. This information may or may not be available to the public.

Sources of data include

Specific examples

Dissertations and Theses

Theses and dissertations are often produced by graduate students as part of their master's or doctoral studies. These works are often used by others in research. According to Juznic (2010, 39), “a thesis is a written text representing the independent research and authorship of a single individual.” Juznic notes that this document is produced to demonstrate that a graduate has subject-matter knowledge in their discipline and is capable of independent research. The structure of a thesis is similar around the world regardless of discipline.

Increasingly, Electronic Thesis and Dissertations (ETD)s are being produced, archived, and circulated. The term ETD refers to “a thesis or dissertation that is archived and circulated electronically rather than archived and circulated in print” (Juznic, 2010, 41). They generally take the form of word processing documents or Portable Document Format (PDF) files. These electronic files are access through web-based services. Full-text databases of electronic theses and dissertations (ETDs) are now the norm for new documents. In the past, theses were printed and placed in university libraries. In some cases, they were placed on microfilm for distribution.

According to Stock and Paillassard (2010, 118), “next to journal articles and eprints, electronic theses and dissertations (ETDs) are for various reasons the most frequent document type found in open archives.” They stress that the rules for defining and referencing these documents are well established. In addition, most students are required to deposit their work in an archive or repository to graduate.

Since 1938, University Microfilm International (UMI) in Ann Arbor has collected, abstracted, and indexed doctoral dissertations from both North America and Europe. This service is now electronic, includes more than 90% of dissertations, and is owned by ProQuest UMI Dissertation Publishing.

Other major dissertation services also exist.

Today, many of these are digitally-born. In other words, they begin as electronic documents and may not even be available in a print format. Older documents are slowly being added.

try itTry It!
Go to Dissertations & Theses Global from ProQuest. Be sure to click the "advanced search" and explore the options. Also try the BROWSE option. Then, browse NDLTD and SIGLE for comparison. Share a 2015 dissertation you find interesting.

Jentery Sayers’s dissertation “How Text Lost Its Source” is an example of the growing number of web-based dissertations. Increasingly, individuals are finding unique ways to share their work.

Citation analysis can be applied to electronic theses and dissertations.

Read Ashman, Allen B. (2013). A citation analysis of ETD and non-ETD producing authors. The Reference Librarian, 54(4), 297-307.

Essays and Treatise

Since early times, scholars have written essays detailing an individual's perspective on a topic. Essays may include criticism, manifestos, arguments, observations, reflections, and many other types of communications. While some essays are published through journals, books, and other formal channels, many others are informally shared as printed documents or web pages.

A treatise is similar in content to an essay, but generally provides more depth. These longer documents are intended to provide the results of investigations, observations, or insights into a subject. Aristotle, Sun Tzu, Euclid, John Locke, David Hume, Thomas Paine, Charles Darwin, Leo Tolstoy, Karl Marx, and others are all known from their treatise.


A wide range of papers fall into the grey literature category. Some examples are listed below.


When you think of a journal article or report, the final product comes to mind. However in many cases, multiple versions of a document are available. Many of these are considered grey literature because they aren't the final, published version.


Whether working on an internal organization project or addressing the requirements of a grant, project documents can be useful in research.

Research projects often contain their own set of documents. These may include:


A report is a document that provides relevant information to a specific audience. While the audience may be the general public, reports can also be used internal to an organization.

try itTry It!
Go to ProQuest: Reports has an option to browse 2000+ reports. How many different report types you can find?

Social Media

From blogs and electronic discussions to email, millions of ephemeral electronic messages are shared every day. These communications can be valuable to researchers.

Marcus Banks (2010) is concerned with the preservation and use of ephemeral grey data such as blog posts and tweets. He notes that findability has also been a problem with grey literature, but the problem is shifting from paper to the need to preserve and access the content on dynamic websites such as social media communications. Examples include

annetteLamb's Personal Connection
I teach courses in children's literature. Some of the most useful sources of up-to-date information come from blogs and electronic mailing lists.

For instance, the YALSA-BK list from ALA is a wonderful source of information about what's happening in libraries with young adult literature. For a complete list of ALA mailing lists, go to http://lists.ala.org/.

As a subject matter librarian, there's no way you can LIKE every Facebook page and join every mailing list with the disciplines. However in many cases, it can be useful to search a blog that you keep bookmarked or the archives of mailing lists.


Standards exist in almost every discipline. Library users may seek information about whether there are standards in a particular area and whether they comply with the standards.

A standard is a rule, condition, or guideline for products, processes, or performance.

Organizations and associations create standards related to their profession.

Governments are often responsible for creating and monitoring standards. In the United States, the Standards.gov website is the entry point for identifying standards. The Regulations.gov website is used to seek public opinions regarding proposed regulations.

Other Materials

Many other unpublished works fit into the category of grey materials such as unpublished manuscripts, newsletters, patents, technical notes, field notes, product catalogs, presentation materials, correspondence, and laboratory notes.

LibGuide on Grey Literature

The categories above just scratch the surface of grey literature. Below are links to LibGuides focusing on sources of grey literature.

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Explore three LibGuides focusing on grey literature. Compare the contents. How are they alike and different? What's missing?

Institutional Repositories

papersInstitutional repositories are collections intended to preserve intellectual property of a particular institution or university.

IUPUIScholarWorks is an example.

"IUPUIScholarWorks Repository is a digital service that collects, preserves, and distributes digital material. Repositories are important tools for preserving an organization's legacy; they facilitate digital preservation and scholarly communication. Submissions in digital form include preprints, working papers, theses and dissertations, conference papers, presentations, student capstone projects, faculty-created learning objects, data sets, and more."

Other examples of institutional repositories are listed below. These sites contain documents across disciplines.

Looking for more? Go to Digital Commons's Institutional Repositories list.

Read at least TWO of the following articles.

Lapinski, P. Scott, Osterbur, David, Parker, Joshua, & McCray, Alexa T. (January 2014). Supporting public access to research results. College & Research Libraries, 75(1), 20-33. Available: http://crl.acrl.org/content/75/1/20.full.pdf+html

Lewis, David W. (September 2012). The inevitability of open access. College & Research Libraries, 73(5), 493-506. Available: http://crl.acrl.org/content/73/5/493.full.pdf+html

Pinfield, Stephen; Salter, Jennifer; Bath, Peter A.; Hubbard, Bill; Millington, Peter; Anders, Janes H. S.; & Hussain, Azhar (2014). Open-access repositories worldwide, 2005-2012: Past growth, current characteristics, and future possibilities. Journal of the Association for Information Science and Technology, 65(1), 2404-2421.

Wesolek, Andrew (2013). Who uses this stuff, anyway? An investigation of who uses the DigitalCommons@USU. The Serials Librarian, 64(1-4), 299-306.

annetteLamb's Personal Connection
I admit to being old. I did my master’s and doctoral work back in the 1980s. My master’s project was typed on an Apple IIe computer and published on a daisy-wheel printer. I submitted my project as a bound volume. Until recently, you had to physically go to the stacks at the Iowa State University Library to read it… like you were going to read it anyway. However, the digitizing team at ISU’s Digital Repository has made it available.

Lamb, Annette Smith (1987). Persuasion and computer-based instruction: the impact of various involvement strategies in a computer-based instruction lesson on the attitude change of college students toward the use of seat belts. Retrospective Theses and Dissertations. Paper 8670. Available: http://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=9669&context=rtd.

It's also available through Dissertations & Theses Global from ProQuest, however a subscription is necessary to access it ProQuest.

It’s unlikely that my dissertation will ever become a best-seller, but it has been cited by four people according to Google Scholar so at least a few people have browsed it!

Beyond universities, there are many other institutions that create depositories. For instance the Animal Studies Repository provide a wide range of data and documents from The Humane Society of America.

try itTry It!
Visit the Animal Studies Repository. Compare this repository to a university repository. How are their missions alike and different?

General Sources of Grey Literature

When seeking out institutional repositories, open access collections, and other sources for grey literature, begin with some search tools specifically designed to access these types of information sources.

To keep track of what's happening with repositories, go to re3data. This Registry of Research Data Repositories provides a starting point to searching a wide range of depositories.

Go to the Ranking Web of Repositories to identify open access initiatives and content that follow good practices.

Grey Literature and the Scholarly Publication Cycle

The publication cycle begins with research question, problem, or idea. During the research process, a number of grey documents may be produced including grant proposals, progress reports, technical reports, conference proceedings, and maybe even a dissertation. Next, articles may be written and another round of documents may be produced including green papers, pre-prints, scientific reviews, and others. Finally, journal articles, reprints, books, and other published works may emerge. Finally, others may create documents citing this research leading to another round in the publication cycle. A single research project may generate dozens of documents at various times during the research and publication cycles.

In order to identify the documents generated during the publication, librarians use the searching forward and searching backwards techniques discussed in Bibliometrics section of the course. Let's review this processes now that we have a better understanding of the grey documents that play a role in the process.

Searching Forward

Scholars often wonder "does my work matter"? Does anyone read or use my work? Has my work had an impact on my field? Forward searching can address these questions as they related to a particular author and the use of his or her work.

  1. Begin with a piece of grey literature such as a dissertation, conference paper, or technical report. Create a citation for this document. Use the links on this page to identify a starting document. Keep in mind that this work should be at least a few years old. Ten to twenty year old articles work best. Need help? Do a Google search for LANDMARK or FOUNDATIONAL works in a particular field. You'll find lots of ideas. If you can't find a piece of grey literature you love, it's okay to begin with the author of a journal article.
  2. Use an Indexing and Abstracting databases, Periodical databases, and other databases to search for the author of this work and seek out journal articles and other publications written by this person on the same or a related topic. Create a bibliography listing citations for each of these works. Use the links on the Periodicals, Databases, and Indexes pages to identify documents. You might also conduct a MetaSearch for this author. Be sure that you've got the correct person.
  3. Use the Citation Indexes including Web of Science Indexes and Google Scholar to determine whether any of the publications identified in steps 1 and 2 have been cited by others. Then, create a bibliography containing a dozen notable works along with the total number found. Find full-text articles on at least a few of these works. How did the original work contribute to the new work?
  4. What's your conclusion? Do you think that the author's work has made an impact? If so, how?

Searching Backward

Backward searching will allow scholars to trace back to see what articles had an impact on a given work. It's also an interesting way to gain insights into an author and their work.

  1. Identify a scholar that is well-published in a specific discipline. This person should appear in an journal article devoted to this person, a subject specific biography reference, or Wikipedia. Create a short biographical sketch and list of their works creating formal citations for each item.
  2. Do an author search in Indexing and Abstracting databases and Periodical databases to locate full-text articles, papers, and books by this person. You may also want to do a Google and Google Scholar search. Select ten works by this author. Analyze the articles. What's the the relationships among these publications? Do they represent different phases of a particular project or different pieces of research? Do the articles follow a particular organizational scheme?
  3. Analyze and compare the bibliographies or reference lists found at the end of the articles looking for patterns. Are the publications listed through self-citations (i.e., the author citing him/herself)? Does this person cite the same people? Are the people cited connected to the author in some way (e.g., same university, same publication, same co-author)?
  4. What's your conclusion? Looking back over this author's body of work, can you find patterns? Can you identify particular people or lines of thought that influenced this person's work?

annetteLamb's Personal Connection
One of my favorite examples of forward citation chasing is the landmark article, What is the History of Books by Robert Darnton. It serves as the basis for my History of the Book course. A search in Google Scholar finds that this article has been cited 525 times. Actually, his book The Great Cat Massacre has been cited 1540 times. It would be fun to create a visualization of this book!

Darnton, R. (1982). What is the History of Books?. Daedalus, 65-83.

Darnton, Robert. The great cat massacre: and other episodes in French cultural history. Basic Books, 2009.



AcademyHealth (February 2006). Health Services Research and Health Policy Grey Literature: Summary Report. U.S. National Library of Medicine. Available: http://www.nlm.nih.gov/nichsr/greylitreport_06.html

Banks, Marcus (2010). Blog posts and tweets: the next frontier for grey literature. In D. Farce & J. Schopfel, Grey Literature in Library and Information Studies. Walter De Gruyter. Available: http://site.ebrary.com.proxy2.ulib.iupui.edu/lib/iupui/detail.action?docID=10424435

Bauder, Julia (2014). The Reference Guide to Data Sources. ALA Editions.

Brown, Christoper C. (2014). Research with U.S. Government Information. In P. Keeran & M. Levine-Clark, Research within the Disciplines: Foundations for Reference and Library Instruction. Rowman & Littlefield.

Farace, Dominic & Schopfel, Joachim (2010). Grey Literature in Library and Information Science. De Gruyter. Available through IUPUI.

Juznic, Primoz (2010). Grey literature produced and published by universities: a case for ETDs. In D. Farce & J. Schopfel, Grey Literature in Library and Information Studies. Walter De Gruyter. Available: http://site.ebrary.com.proxy2.ulib.iupui.edu/lib/iupui/detail.action?docID=10424435

Kellam, Lynda & Peter, Katharin (2011). Numeric Data Services and Sources for the General Reference Librarian. Elsevier. Good Preview Available: https://books.google.com/books?id=bxltAgAAQBAJ

Reitz, Joan M. (2014). Online Dictionary for Library and Information Science. Libraries Unlimited. Available: http://www.abc-clio.com/ODLIS/odlis_a.aspx.

Stock, Christiane & Paillassard, Pierrette (2010). Theses and dissertations. In D. Farce & J. Schopfel, Grey Literature in Library and Information Studies. Walter De Gruyter. Available: http://site.ebrary.com.proxy2.ulib.iupui.edu/lib/iupui/detail.action?docID=10424435

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