Depending on your topic, you may want to use dissertations or theses in your research project. The databases below contain the largest collections of them. Some are available online; if you want to use one that is not, you can request interlibrary loan service.
The Baylor Libraries collections are very strong, but obviously we don't have every book on every topic. To see what other books exist out there, use the WorldCat database (linked below). From the WorldCat record for a given item, you can use the BU Info Links to launch an interlibrary loan request and have a copy shipped here for your use. For more information, see the OsoFast tab above.