These databases are not specifically devoted to HPS sources; they are databases for social sciences, philosophy, and history. They do have articles about the history, philosophy and sociology of science---they just contain articles on other things too. They're still probably your best bet for finding HPS articles, as long as you include science terms in your search.
These are more like encyclopedias than databases, but each entry has references/citations. They're a good way to figure out where to start with your research and get a quick overview. Sage Research Methods also has some tools (a project planner, for example) that you might find helpful.