Do I have to translate primary and secondary sources into English for a dissertation?
I wrote my dissertation about translation in Spanish, and I had to quote several non-Spanish speking authors (English, German, Catalan, French). I decided quoting in the original language and adding the translation in a footnote. When there was a published Spanish translation of the quote, I used it. But if not, I translate it myself.
However, it's a good idea to ask your supervisor if there is a style guide for this issues.