Kibler, William W., and Grover A Zinn, eds. A one-volume reference that focuses on France. Strayer, Joseph R., gen. Dictionary of the Middle Ages . A major reference source in this area.
Bibliographies are mostly in English.
Szarmach, Paul E., and M. Teresa Tavormina, Joel T. Rosenthal, eds. A one-volume reference that focuses on England. Bibliographies, Guides, and Handbooks Cambridge Medieval History . Each chapter has been written by a specialist and each volume concludes with an extensive bibliography. The emphasis is on political and economic history but there are also chapters on medieval universities, language and learning, and chivalry in the Middle Ages.