1997- The Luxembourg Convention on Grey Literature; expanded New York 2004
“...that which is produced on all levels of government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers i.e. where publishing is not the main activity of the producing body”
Dissertation & Thesis
Reduce publication bias
More access to global literature
Often more current
Clinical trial registries
Studies reported in languages other than English
• To reduce bias, multiple databases need to be searched
• Suggested main databases to be searched in health care field
• Search specialized databases or websites for your topic additional to the suggested main databases
• Search scientific information packets, e.g., manufactures of products under review, for specific topics
• Search cited references of main literature search results
•Hand search in targeted journals
• Keep personal communications (e.g., principal investigators, colleagues, authors, experts in a discipline) to get subject experts' opinions on resources and search strategies
• Conduct Google/Google Scholar search to find additional documents
•Search strategy may be influenced by inclusion and exclusion criteria
•Search grey literature
Techniques for harvesting terms
One technique of collecting terms in PubMed
Methodology filters can help to get rid of undesirable study designs so as to reduce the size of a large retrieval. However systematic review attempts to maximize sensitivity in terms of retrieving all relevant documents. Therefore it is always preferable not to employ filters.
Sometimes retrieval sets are literally unmanageable. You‘d probably want to implement a methodology filter.
If you have to limit, use at all possible validated filters, which have been tested against gold-standard sets of bibliographic records.