CLINICAL TRIALS
According to the MeSH scope note, a clinical trial is "a work that reports on the results of a clinical study in which participants are assigned to receive one or more interventions so that researchers can evaluate the interventions on biomedical or health-related outcomes".
You can find clinical trials in databases, but there are also specific resources where you can find clinical trials, in some cases before they are published in journals:
CITATION DATABASES & PEARLING
Citation databases are multidisciplinary, and their citation searching functions allow for "pearling" - trawling through citations and "cited by" articles to pick up some extra articles that may have been missed in your database searching. You can do this by doing a rough search to get started, or plug in one of your "gold" articles and see what you find. The two main citation databases are:
GREY LITERATURE
Grey literature is research that has not been published commercially and therefore might not be available in the usual databases and journal collections.
Examples of grey literature include government reports, conference proceedings, theses, policy documents, and clinical trials (as above). Note that grey literature is not necessarily peer-reviewed, and should be evaluated carefully.
The Library's Grey Literature guide has more information, including how to find and evaluate grey literature, and some useful sources in various subject areas.
HAND SEARCHING AND MORE
A full systematic review may require even more thorough searching, including:
- Reviewing the contents of the major journals and conference proceedings in your subject area page by page ("hand searching")
- Contacting authors of key studies, or known experts in the field
- Checking through the reference lists of key articles.
