Review materials are a good way to familiarize yourself with trends and key ideas in a field of study. These are usually annual or monthly cumulations of articles or citations to articles that give you a brief summary of research and findings on a particular topic.
The Cochrane Library provides access to systematic reviews in addition to other sources of reliable information, from other systematic review abstracts, technology assessments, economic evaluations and individual clinical trials. Includes Cochrane Database of Systematic Reviews(CDSR), Database of Abstracts of Reviews of Effects (DARE), Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Methodology Register (CMR), NHS Economic Evaluation Database (NHSEED), and Health Technology Assessment Database (HTA).
Encyclopedias and bibliographies review the state of research in an area or on a topic and refer you to additional sources. Encyclopedia entries often have a list of works cited at the end that point you to relevant readings while bibliographies list foundational citations on a given topic.