1. Search in multiple places. Don't just settle for the first result. It's worth skimming several results and using sources in conjunction with one another.
2. Try multiple different search phrases in multiple places. For example, if your topic is human dissection, try "human dissection," then try "Vesalius," then try "Galen's anatomy." And make sure to try each in multiple databases/resources.
If you're still missing key information from the above resources. Try the below databases. If you get too many results or results that are too complex to read, filter by "source type." Magazine articles are an ideal type of source for this project.
