If I wanted to make it my life's goal to assemble all the original documents regarding life as a Partisan and synthesize a thesis or book from these; first of all would the greater difficulty be gaining access to these documents (if enough exist), or learning exactly what languages?

I'm thinking first of all German as they tended to keep more records perhaps than the Partisans themselves, then I'm imagining everywhere from the Baltic states' language groups to Polish, Russian, Hebrew, Ukrainian, to all of the Yugoslavian languages.

Also if you have any tips for an amateur with a dream regarding study of these issues that would be much appreciated.