In this project, you should have at minimum of 2 sources in each of the following categories:
MeSH stands for Medical Subject Headings and is a controlled vocabulary used within PubMed and other search tools available through the National Library of Medicine.
When searching PubMed, these can really help you narrow your searches, for instance try to use/combine some of the following:
Selected sources for finding high impact research.
Within most databases, click on the FullTextFinder link to get options for obtaining the full text of the article.