Our catalog, WorldCat, lists Boise State materials first, and then lists items held at other libraries. Books and other materials that we own will be labeled "Boise State University Albertsons Library."
If a book says that it is "Held by Other Idaho Libraries," it's worth clicking on the title to get the full record, and then look at Libraries Worldwide to see a list of libraries that own the title. You might find that a library up the street owns a copy.
If a book says Held by other libraries worldwide (which means that the book isn't held by a library in Idaho), current Boise State University students, staff, and faculty can click the Request item through Interlibrary Loan link to request the book. If you aren't affiliated with Boise State University, ask your public library about their interlibrary loan service.