From the webpage:
OATD aims to be the best possible resource for finding open access graduate theses and dissertations published around the world. Metadata (information about the theses) comes from over 600 colleges, universities, and research institutions. OATD currently indexes over 1.5 million theses and dissertations.
A search for “topic maps” as a phrase turns up thirty-six matches.
Try it for yourself: OATD search: “topic maps”
Yes, the total for RDF is substantially higher.
But I take that as an incentive to do a better job spreading the word about topic maps in academic circles.
I first saw this at: Theses and Dissertations Available Through New Open Access Tool by Africa S. Hands.