Besides using interlibrary loan to bring the necessary sources here for your use, we will do Special Purchases for you given circumstances. So be sure to talk with one of the Research Librarians about your needs. This does require planning, as most orders take some weeks to arrive and be processed.
Last but certainly not least, there are lockers for those doing thesis work. There are a limited number which are assigned on a first-come, first-served basis by the Circulation staff.