Grey literature is literature produced by government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers. A widely quoted definition of grey literature is "literature which is not readily available through normal book-selling channels, and therefore difficult to identify and obtain" (Wood, 1982). Grey literature includes theses and dissertations, conference papers and proceedings, reports (such as white papers, working papers, internal documentation), government documents, technical notes and specifications, proposals, datasets/statistics, policies/procedures, patents, unpublished trial data, regulatory data, speeches, urban plans, test instruments, pre-prints, company information, social media, and more. A full list of Document Types in Grey Literature is provided by GreyNet International.
It is crucial to note where the term “grey literature” derives from. Grey literature comes from the uncertainty of the status of this information. However, in cases where there may not be much information on a topic in peer-reviewed research, grey literature may prove a very valuable source of information and introduce alternate viewpoints. Additional benefits to using grey literature include:
Grey literature may present a number of challenges for the researcher, making it difficult to identify and find. Consider the following when searching for grey literature:
Review the Evaluating Information Guide to help determine if a resource is appropriate for use in your research. The AACODS checklist is designed to enable evaluation and critical appraisal of grey literature.
The techniques below outline suggestions for locating select types of grey literature, as well as searching more broadly online. Please contact the Library with any questions.
Clinical trials are a form of grey literature and can inform current research conducted by organizations, Federal agencies like the National Institutes of Health, academic institutions, and individual health care providers. These studies investigate the effectiveness of new treatments, interventions, drugs, procedures, and devices in order to improve health outcomes for a specific population.
Several Library databases and online resources provide access to full-text clinical trials. See our Clinical Trials Guide for detailed instructions.
If you are unable to locate the full text for a particular clinical trial, you may submit an Interlibrary Loan request for the material.
A conference proceeding is the published record of a conference, congress, symposium, or other meeting sponsored by professional association or society. Proceedings typically include abstracts or reports of papers presented by the participants. When the entire text of the papers presented is included, they are called transactions. For more information, see the FAQ: Are conference proceedings peer reviewed?
Conference papers and proceedings can be challenging to find because they may take several years to be published or may not be published at all. They can be published in various formats including books, abstracts, and journal articles; and, they may be deposited only in an author or institutional repository.
Some Library databases, like ProQuest, make it easier to search for these types of documents by allowing you to limit your search to Source type. Other databases that provide conference proceedings include IEEE Xplore, ACM Digital Library, LearnTechLib, CINAHL, and ERIC. These databases are available from the A-Z Databases page.
Previously published dissertations and theses can be a great source of inspiration for your own dissertation topic. You can access millions of full-text dissertations and theses from the Library. Go to the Library’s Dissertation Resources page to see a list of databases. You can specifically access dissertations from alumni via ProQuest Dissertations and Theses @ Northcentral University. Or you can explore the 3 million full-text dissertations available through ProQuest Dissertations and Theses Global.
For additional information and resources, see the Finding Dissertations Guide.
Government documents are an important primary source of information on a wide range of issues. Most government documents can be found through official government websites.
A preprint is an author's working version of a research manuscript prior to publication. In most cases, they can be considered final drafts. Preprints may also be referred to as working papers or unpublished manuscripts. Preprints have not gone through the peer-review process, nor have they been improved upon by the publisher (e.g., formatting, copy-editing, technical enhancements). It is very important to critically evaluate preprint publications. Because the peer review process can take three to six months, preprints are a way to provide valuable research results and discussion ahead of publication. They are also a great way to locate information on emerging or rapidly changing research topics.
Preprints are published electronically and made publicly available on large databases or preprint repositories. The techniques below describe how to locate preprints in the Libray and online. Note when searching for preprints in Library databases, you do not want to select the peer-reviewed journal limiter.
EBSCO Business Source Complete
In Business Source Complete, select the Advanced Search screen. Scroll down to Publication Type and select Working Paper.
In ProQuest Central, select the Advanced Search screen. Scroll down to the Source Type limiter and select Working Papers.
In PubMed Central, select the Advanced Search Builder. Enter the preprint[filter] command along with your topic keywords.
Web of Knowledge
After conducting a search in Web of Knowledge (Web of Science), check the Early Access box under the Quick Filters on the left-hand side of the screen.
Research reports contain the results of research projects, investigations, and surveys, and are usually published by the funder or the body undertaking the research. They can be found by searching the websites of subject associations and research organizations in addition to NU Library’s databases.
For example, you may limit your Roadrunner Search results to reports by using the limiters on the left-hand side of your results screen.
Social media and other Web 2.0 applications have become a valuable medium for for experts, governments and academics to publish new information and analysis outside of the traditional publishing arrangement. These sites may be useful as a way to disseminate information/results, follow experts and trending topics, and as a forum for exchange of ideas.
For a thorough overview of Web 2.0 grey literature sources, please see the Grey Literature: Grey 2.0 Guide from New York University.
Grey literature repositories are curated collections of grey literature sources. You can use these collections to search or browse for resources for use in your research.
There are a couple of Google custom searches that narrow your results to a specific type of organizational website. This may be helpful step when searching for grey literature. Enter your search terms into these pre-built basic search boxes to see your filtered results.
Google allows you to limit your search results to a particular domain (e.g., .edu, or .gov). This can be particularly helpful if you are looking for grey literature as you are more likely to find reliable content from organizations rather than commercial content.
Look for the "site or domain" box in Google's Advanced Search options and enter the domain you'd like to search, as shown below.
You can also do this by adding site:.edu (or .org, .gov, etc) to the end of your search terms in any Google search box. For example, to find articles about “ethical leadership” published on government websites, enter the terms "ethical leadership" site:.gov, as shown below.
Google also allows you to search for results with a specific file type (example: .pdf, .doc, .ppt, .xls). This is also helpful when looking for grey literature as government and organizational reports are more likely to be available as PDF or Word documents. Datasets may be provided as Excel files.
Look for the "file type" box in Google's Advanced Search options and select the file type you would like to search, as shown below.
You can also do this by adding filetype:pdf (or .doc, .ppt, .xls, etc.) to the end of your search terms in any Google search box. For example, to find PDF documents about “ethical leadership” enter the terms "ethical leadership" filetype:pdf, as shown below.