1. Many times a database will allow you to limit your search results by document type. Usually there is some sort of drop down menu present from which you can select a report or review of some type.
2. Many databases will also allow you to limit your results to just peer-review journals. Most legitimate studies and reports are published in these types of publications. Please see the "Scholarly Article" tab to learn more about peer-review journals.
3. Finally, when entering search terms, sometimes you can locate a study, review or report by adding those words to the end of your search phrase or entering the term in a separate search box. Example: climate change study