Library of Congress Classification (call numbers) are useful to know for your area of concentration - it helps you locating books in the library stacks. Check the links below for detailed information about call number ranges. Each file shows the overview first; subsequent pages shows very detailed breakdown of the topic.
UNM LIbraries has more than 4,000 e-books that deals with some aspect of medieval history, literature, philosophy, etc. Here is a very small selections to give you an idea of the scope.
Conduct a search from the UNM Library home page for: Medieval and then limit to:
Below is a sample with direct links to the ebooks