If you’re interested in learning more about the middle ages, some of the books below might be of interest. I have not included links to online stores because I don’t want to favor one store over another.
Bishop, Morris. The Middle Ages. Boston: Houghton Mifflin Harcourt, 1968.
Dales, Richard C. The Scientific Achivement of the Middle Ages. Philadelphia: The University of Pennsylvania Press, 1989.
Stephenson, Carl. Medieval Feudalism. Ithaca: Cornell University Press, 1956.
Ziegler, Philip. Black Death. New York: Harper Collins, 1971.