Catalyst lists the collections of both Carleton and St. Olaf.
To find books held at libraries beyond Carleton and St. Olaf (and request them through Interlibrary Loan)
Books and more from other libraries
Request books you find on WorldCat using the "Request Via Illiad" links.
Academic reference sources are a great set of tools to use alongside article databases. Consulting a signed article is like asking an expert about a topic. Use these short articles to get a sense of how research in the field is organized what language is used (gather keywords to improve your searches elsewhere), find ideas for shaping your question, and see vetted lists of books and articles (better than 3,000 results from a search).
This is a short list of what is available. Talk to a librarian for ideas of other places to search or peruse the Databases list.
If you want to venture into research from other disciplines, a good way to narrow your options is to turn to research guides for those fields.