You can use the same searches you used effectively in the catalog (both subject and keyword), and get a lot more results! WorldCat is the closest thing there is to a universal library catalog. It includes the holdings of thousands of libraries worldwide.
Try searching the full text of books with Google Books. You’ll get results, almost guaranteed (whether they’re relevant is another story!).
Use Interlibrary Loan to request articles or books or chapters of books at no cost to you.
Follow the link below. (If you're a first-time user, you will first need to register yourself after logging in).