Encyclopedia of the Middle Ages
"A collaborative work of over 600 scholars from more than forty countries, the Encyclopedia of the Middle Ages provides 3,000 concise and detailed articles on all aspects of the period from the fifth to the fifteenth century. It explores art, architecture, religion, law, science, language, philosophy, and theology, as well as cultural, religious, intellectual, social and political history. With a focus on focus on Europe and Christendom, the Encyclopedia also covers the rise of Islam and people of other cultures with whom Europeans came into contact." One of the Oxford online research volumes.