In a subject search you use the subject headings established by the Library of Congress to locate materials on your topic. One way to identify appropriate subject headings is to find a good book on your topic through a keyword search in the library catalog and see what subject headings are used to describe that book. You can click on those subject headings to find more materials on the same subject.
Other Library Catalogs
If you can't find the item you're looking for at Iona, and you don't have time to wait for Interlibrary Loan to deliver the book to you, it might be worthwhile to check the catalogs of some of the libraries in the area. Most libraries will give you special permission, as an Iona student, to access their collections in a limited fashion, even if you are not a member of that library.