The AHA Guide to Historical Literature will get you started on any time period anywhere in the world. The link is to the online version.
Lack of systematic quality control means critical evaluation of Web sites is crucial. When evaluating web resources, consider:
Taken from: Ramage, Bean and Johnson. The Allyn and Becon Guide to Writing. 5th Ed. customized for Marquette University. Boston: Pearson Education, Inc., 2009: 602.