You must be concerned about the quality of the studies, and a good database will be a cornerstone to you. There are some protocols that guide a well done systematic review. I suggest you the PRISMA statement, PICO strategy, and there are some workshops realized by Cochrane that will help you. There are good databases like MEDLINE/ PUBMED, SCIELO, LILACS, EMBASE and Cochrane database. You will need two more members that will work with you. I wish you a good work.