If you're searching for systematic reviews of evidence, you may find Epistemonikos a useful resource. Unlike the Cochrane Library, this contains systematic reviews from many sources (it does also contain some primary research articles that have been included in the reviews, but the main focus is systematic reviews).
Systematic reviews are an excellent source of high-quality evidence, and should use a clearly formulated question and systematic and explicit methods to identify, select, and critically appraise relevant research, and collect and analyse data from the studies that are included in the review.
While most of the systematic reviews included will be included in other sources such as Medline and EMBASE, they are not always easy to locate (though we have added some search filters to the Knowledge Navigator page to make this easier).
We've added Epistemonikos to the Systematic Review section of our Knowledge Navigator, where you'll find useful guidance and sources for locating many different types of evidence. Alternatively, why not simply ask us to conduct an evidence search for you?.