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The objective of this chapter, and of the original in the 1994 edition of this handbook, on which this one is based, is to provide methods of retrieving hard to find literature and information on particular areas of research. 1 We begin by briefly outlining the many developments that have taken place in retrieval of hard-to-find research results over the past decade, including the formalization of this work as a distinct research specialization. Although we continue to focus on how to retrieve hard to find literature, developments in research synthesis methodology allow us to place retrieval of this literature in the context of the entire research synthesis process. The key point is that there is a critical relationship between the reliability and validity of a research synthesis and the thoroughness of and lack of bias in the search for relevant studies. Since 1994, changes in technology and in scholarship have created new challenges and new opportunities for anyone interested in reading or synthesizing scientific literature. As the Internet, the Web, electronic publishing, and computer-based searching have developed, grey literature has both grown and become more accessible to researchers. Grey literature comprises an increasing proportion of the information relevant to research synthesis; it is likely to be more current than traditional literature and channels for its distribution are improving. As a result, sifting through the grey literature, as well as locating it has become a major task of the information retrieval phase of a research synthesis. The emergence of the idea of grey literature is not new and the concept is beautifully illustrated in a quotation by George Minde-Pouet in 1920, cited by Dagmar Schmid-maier: "No librarian who takes his job seriously can today deny that careful attention has also to be paid to the 'little literature' and the numerous publications not available in normal bookshops, if one hopes to avoid seriously damaging science by neglecting these" (1986). Acceptance of the term dates back to 1978. A seminar at the University of York in the UK was recognized as a milestone for grey literature as a primary information source and resulted in the creation of the System for Information on Grey Literature in Europe database (SIGLE), which is managed by the European Association for Grey Literature Exploitation (EAGLE). Unfortunately, this database has not been updated since 2004, and its future is uncertain. The first scholarly society devoted to the study of grey literature, the Grey Literature Network Service (Grey-Net), was founded in 1993. This group sponsors an annual international conference, produces a journal, and maintains a list of grey literature resources in the service of its mission to "facilitate dialog, research, and communication between persons and organizations in the field of grey literature⋯. [and] to identify and distribute information on and about grey literature in networked environments" ( The work of this group has highlighted the fact that traditional published sources of scientific information can no longer be counted on as the primary repositories of scientific knowledge. Copyright © 2009 by Russell Sage Foundation. All rights reserved.



Book title

The Hand. of Res. Synthesis and Meta-Analysis, 2nd Ed.

Publication Date



103 - 125