The Oxford Dictionary of the Middle Ages covers key aspects of the medieval world, 500-1500, including the Byzantine Empire, Islamic dynasties, and Asiatic peoples of the period.
Oxford Bibliographies Online Medieval Studies combines an annotated bibliography with detailed encyclopedic entries on people, events, and cultural aspects in medieval studies. New entries are added on an ongoing basis. To see a complete list of articles, click on "About This Subject" in the lefthand column and scroll down the page. The Advanced Search screen allows searches in other subscribed bibliography modules such as Art History, Islamic Studies, and Philosophy as well as Medieval Studies.
Additional reference works are housed in Alcove 3 of the Main Reference Collection. These include Encyclopedia of the Middle Ages, edited by Andre Vauchez , 2 volumes, D114 .E53 2000; Key figures in medieval Europe: an encyclopedia, edited by Richard Emmerson, D115 .K49 2006; and The medieval world, edited by Peter Linehan and Janet Nelson, D117 .M43 2001. The Dictionary of the Middle Ages, edited by Joseph Strayer, D114 .D5 1982, 13 volumes is older, but still useful. There is one supplement volume.
Also in Alcove 3 are some encyclopedias of the medieval period in specific countries: Medieval England, DA129 .M43 1998; Medieval France, DC33.2 .M44 1995; Medieval Germany, DD157 .M43 2001; Medieval Italy, DG443 .M43 2004; Medieval Scandinavia [Denmark, Sweden, Norway, Finland],, DL30 .M43 1993; Medieval Iberia [Spain and Portugal], DP99 .M335 2003; Medieval Islamic Civilization, DS36.85 .M434 2006; Medieval Jewish Civilization, DS124 .M386 2003.