Try searching the name of the work or the author name in the following database:
For a refresher on the difference between primary sources and secondary sources, click here.
The following may refer you to good primary sources on your topic.
They can also help you identify relevant historical figures authors, or keywords for searching library databases.
Combine keywords for different kinds of primary sources with keywords for your topic to find them in the library catalogue.
Primary source keywords
medical botany early works
Sample Catalogue Searches for HPS318 Primary Sources at UTL
Type your topic keywords into these major databases, and see what comes up.