References in dissertations should follow the same principles as in scientific publications. Concerning Wikipedia, see these discussions:

https://www.researchgate.net/post/Citing-Wikipedia

https://www.researchgate.net/post/Wikipedia_as_source_of_knowledge_and_citation

https://www.researchgate.net/post/Does_anyone_take_Wikipedia_contents_while_writing_a_research_paper

https://www.researchgate.net/post/Is_it_ok_to_cite_Wikipedia_content_in_our_research_articles

https://www.researchgate.net/post/Do_you_feel_that_Wikipedia_is_a_useful_source_of_information_for_your_teaching_and_or_scientific_endeavors