WorldCat is a combined catalog of books held in libraries all over the world. All of the major libraries in the United States participate in WorldCat, so you can use WorldCat to discover books that are not available in South Carolina and then request books via Interlibrary Loan.
Begin your search on WorldCat.org in the same way you would search the library catalog. You will probably want to limit your search to just books in the left column. Other facets for limiting your search include language, publication date, and author.
On each book's page, you will see much of the same information you would find in the Classic Catalog, such as tables of contents, subject headings, and publication information. You will also see a list of nearby libraries that own the book. Use this information to determine whether you should request the book via Pascal (for libraries in South Carolina) or interlibrary loan (everywhere else).