QuickSearch and Google Scholar are good for finding ebooks and chapters and journal articles.
Jessica uses a not-so-well-known resource (The TRIP database, where T.R.I.P. is Turning Research Into Practice) for finding extra high-quality material, including:
Like Google Scholar, it is very easy to search but some of the items in the results might require an institutional login to access:

The Joanna Briggs Institute COnNect+ database also has systematic reviews, evidence summaries, and best practice recommendations, but it has two advantages:
It has a very simple search engine, so do not expect sophisticated searching.


Cochrane Library contains very high-quality evidence-based double-checked systematic reviews with recommendations on whether a treatment is actually beneficial or not (whether it is better than placebo), whether all similar studies on the same treatment show the same benefits, and comparisons of one treatment versus another.
Cochrane systematic reviews (and systematic reviews in general):
Search interface:

Results:

Important sections to read:

