You may make use of the following thesis databases for your research.
Kadir Has University Theses
https://gcris.khas.edu.tr/handle/20.500.12469/1805
Higher Education Council Thesis Catalogue
https://tez.yok.gov.tr/UlusalTezMerkezi/
ProQuest Dissertations & Theses
https://icproxy.khas.edu.tr/login?url=https://search.proquest.com/pqdtglobal/