Cochrane Library consists of the following:
Cochrane Database of Systematic Reviews - full text available.
Cochrance Central Register of Controlled Trials (CENTRAL)
Cochrane Methodology Register. A bibliography of publications that report on methods used in the conduct of controlled trials. They do not contain the full text of the article.
Database of Abstracts of Reviews of Effects (DARE). It contains abstracts of systematic reviews not yet carried out by the Cochrane Collaboration. Each abstract includes a summary of the review together with a critical commentary about the overall quality.
Health Technology Assessment Database. Brings together studies of the medical, social, ethical, and economic implications of healthcare interventions from around the world.
NHS Economic Evaluation Database. Systematically identifies economic evaluations from around the world, appraising their quality, and highlighting their relative strengths and weaknesses.
There are a number of ways of retrieving trials from PubMed:
In addition to the Cochrane Library and Medline, there are many other important sources of trials, particularly randomized controlled trials as listed below: