Recommended multi-disciplinary databases:
Dissertations and Theses (ProQuest) - an index (not the full text) of all doctoral dissertations and some master-level theses in North America and selected European schools. Abstracts available for content published since the 1980s. Locating dissertations does not guarantee, however, you can get the material from the home institution. Institutions may not lend their sole copy of a dissertation, but ProQuest will sell you a copy for a fee.
Note authors of interest and check their publication record, in case the dissertation or future research was published elsewhere.
Some scholars have had luck requesting a copy of the bibliography of a dissertation, rather than the entire project.
Another collection of theses, focusing on electronic theses from European research libraries:
DART-Europe E-theses Portal (DEEP) is a growing collection of theses and dissertations from nearly 300 universities in 17 countries.