Ideally, everything you find through the library's tools would be legitimate e.g. peer-reviewed and/or scholarly. That is not always the case. Whether you have identified a resource through Google or a scholarly index like Proquest Politics you must critically evaluate every source before you use it.
There are a number of convenient checklists that have been developed to help you evaluate websites. Two of the most well-known checklists are included below: RADAR and CRAAP. Either option provides a list of questions to help you evaluate the information you retrieve from the web, whether scholarly in scope or not.
Adapted from Mandalios, J. (2013). RADAR: An approach for helping students evaluate Internet sources. Journal of Information Science, 39(4), 470-478.
For a handy CRAAP worksheet, refer to this rubric attributed to Central Library MCHS. It prompts you to score a site on each of the CRAAP criteria to come up with a final score that could range between a potentially "highly questionable source" to a "excellent source for research."
Known more popularly as "JCR," Journal Citation Reports provides evaluation of Social Sciences journals based on citation data, or how often an article is referenced by researchers.
Sorting by Journal Impact Factor (JIF) using Journal Citation Reports (JCR), determine which journals in a discipline are making the greatest contribution to the publishing history of an idea by measuring citation frequencies. In Political Science, JCR ranks approximately 187 journals against each other.