Oxford Academic Journals (this is an hybrid open access site so not all articles are available for free)
"PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites." If you cannot access the full text article, try searching for it in our databases or searching for it on the Internet.
You will need to evaluate articles based on the characteristics of scholarly articles (see chart above).
"Google is not an academic source, or indeed, a source at all. ... Google Scholar is a branch of the Google search engine that strives to locate only scholarly sources, and bases the relevancy of an article on how often it was cited and who it was published by" (http://libanswers.uwinnipeg.ca/faq/156269 ).
You will need to evaluate articles based on the characteristics of scholarly articles (see chart above).