Formerly known as Dissertation Abstracts. Provides full text access 1997-present to most dissertations from U.S. institutions. Provides indexing information to dissertations 1861 - present.
Many universities, including OU, no longer submit the full text of their dissertations in this database. Instead they post their dissertations in an institutional repository (at OU, this is called SHAREOK)
Dissertations are indexed from 1861 to the present, so even if full text is not available, you can get an abstract and information about the author, year, advisors, etc.
If the dissertation is not available electronically, you can order through interlibrary loan.