I am completing a master's by research (in Humanities), and thus shall be writing a thesis with no class work. I am using both a mixture of primary and secondary source but one item that has me a bit unsure is the use of other master's theses. Is there an expectation at the master's level that you would only consult documents at a higher level (PhD and up)? I know the simple answer would be to ask your advisor, which I intend to do, but I wondering it their any accepted academic practice or principle on the issue?
Should or can I refer to (and cite) other master's thesis as source material or should I be only using material that would be considered above the master's level, such as PhD theses?