You can search databases such as these for journal articles. Most provide article citations and abstracts. In many cases, you can find full text of the articles.
Practical clinical reference tools for quick access to synthesized information.
In Evidence-Based Practice (EBP), research studies are ranked in a Hierarchy of Evidence. Information sources described near the top of the pyramid are the most thoroughly reviewed and synthesized. The type of sources you need to seek will depend on the type of question you need to answer.