Some key sources for locating international theses include:
ProQuest Dissertations & Theses Global - Full Text
ProQuest's multidisciplinary collection of dissertations and theses spanning from 1743 to the present day.
WorldCat is the world’s most comprehensive database of information about library collections. You can refine your search by selecting format option of theses.
Networked Digital Library of Theses and Dissertations (NDLTD)
Provides access to free, electronic full text of theses from participating universities.
Open Access Theses and Dissertations
Database of open access theses and dissertations published around the world.
Google Scholar provides a simple way to broadly search for scholarly literature, including these
Asia and the Pacific
Europe and the UK