BASE (Bielefeld Academic Search Engine) – academic open access web resources including theses.
CORE – (COnnecting REpositories) aggregates all open access research outputs from repositories and journals worldwide and make them available to the public.
NDLTD – provides a very useful list of links to theses portals from various countries around the world.
OATD – provides a portal for open access theses published around the world. Over 1000 colleges, universities and research institutions are indexed.
OpenDoar – provides a quality-assured listing of open access repositories around the world.
OAIster – a global catalog of digital resources from open archive repositories – includes theses.
PhdData.org – universal index of Doctoral Dissertations in progress (need to register with this site).
WorldCat – the world’s largest network of library content and services. Advanced search option provides a limit by content type ‘thesis/dissertation’
Commercially available thesis providers
ProQuest Dissertations and Theses – provides international collections of full text electronic theses and dissertations to subscribed users through University Library webpages.