Each database has rules that govern how it operates. It can be helpful to review the rules before searching.
Ultimately, be sure you consult with a librarian or information specialist before undertaking your searches for original studies. Searching online databases is a specific skill that librarians are trained to do. A librarian does not have to be an expert in the subject matter-- that is your job. But a librarian will know the best way to formulate a search strategy which yields the best results.
Be sure you choose a librarian who has been trained in performing searches for systematic reviews. And be prepared by completing the Systematic Review Worksheet to Prepare for Database Searching.
You will need to be affiliated with the University of Texas School of Public Health to access these resources.
Don't forget to use the appropriate SR filters if you want to limit your search to specific types of studies.
There is currently no filter for secondary data analysis; one is being developed.
The databases listed below cover tens of thousands of journals and even special reports that get indexed by the databases. Work efficiently-- start with journals, then look at other resources.
If you are working on an intervention study, whether behavioral or pharmaceutical, take a look at clinical trials databases to determine if there might be additional data that could affect the results of your systematic review. However, a big caveat is that many of the databases were developed fairly recently. Studies done more than 10 years ago with null results (or less-than-favorable compared to the control) may be impossible to find.
For general reference assistance, please click here: http://askus.library.tmc.edu/
For Faculty and Staff consultations, please click here: http://library.tmc.edu/services/research_consultation/