Make sure to select "THESES/DISS" under "material type" to limit the search to show only dissertations and theses in the results. Dissertations and theses published by Regent students before 1988 are not available electronically, and can only be located through this method.
Although the WorldCat Dissertations & Theses database is only available by subscription to FirstSearch, WorldCat is available for free. The advanced search screen allows you to limit by Format >> Book --Thesis, Dissertation. The link provided above will direct you to WorldCat's advanced search screen.