Encyclopedias are great for:
Specialized Scholarly Subject Encyclopedias: Middle Ages
Dictionary of the Middle Ages. 12 vols. 1982-1988. (Olin Reference D 114 D55+; also Uris Reference) Articles cover roughly the years 500-1500 A.D. in the lands of the Latin West, the Slavic world, Asia Minor, the lands of the Caliphate in the East, and the Muslim-Christian areas of North Africa. Some entries are only of definition length (e.g. Avignon), but others are more historical and lengthy (e.g. Byzantine Empire, Constantine I, Arms and Armor). Bibliographies are mostly in English.
Encyclopedia of traditional epics (Olin Library Reference Oversize PN56.E65 E64x 1994 +)
Trade, travel, and exploration in the Middle Ages: an encyclopedia. Unique and highly recommended. (Olin Library Reference HF1001 .T7x 2000 +)
The Crusades: an encyclopedia (Olin Library Reference Oversize D155 .C78 2006+)
Encyclopedia of the crusades (Olin Library Reference Oversize D155 .A6x 2003+)
Encyclopedia of medieval pilgrimage (Olin Library Reference Oversize BX2320.5.E85 E53 2010 +)
Medieval Archaeology : an Encyclopedia. 2001. (Olin Reference D125.M42x 2001+) A substantive up-to-date encyclopedia of medieval archaeology, with entries for sites (Sutton Hoo, e.g.), areas (Pre-Viking Scandinavia), ethnic/culture groups (Vikings, Visigoths), artifacts (Stoneware) and activities (Hunting, Cloth-making).
The Catholic encyclopedia and The New Catholic Encyclopedia Beyond the subject of Catholicism to include science, literature, art and civilization. Articles sometimes include bibliography of primary and secondary sources.
The Wiley Blackwell Encyclopedia of Anglo-Saxon England. 2nd ed. People, places, social groups. Most articles contain concise bibliographies.
Medieval folklore: an encyclopedia of myths, legends, tales, beliefs, and customs. Santa Barbara, Calif. : ABC-CLIO. (Olin Library Reference GR35 .M43x 2000+)
Medieval folklore: a guide to myths, legends, tales, beliefs, and customs. Oxford ; New York: Oxford University Press, 2002. (Olin Library GR35 .M43x 2002 and Olin Library Reference GR35 .M43 2002)
Medieval Scandanavia: An Encyclopedia. (Kroch Rare and Manuscripts Reference and Olin Reference DL30 .M48+).
Medieval folklore : a guide to myths, legends, tales, beliefs, and customs.(Olin and Uris Reference GR35 .M43 2002)
Ancient Europe 8000 B.C.--A.D. 1000: encyclopedia of the Barbarian world. (Olin Library Reference D62 .A52x 2004+)
Encyclopedia of barbarian Europe: society in transformation. (Olin Library Reference D135 .F73x 2003+)
Medieval Islamic civilization: an encyclopedia. (Olin Library Reference DS36.85 .M434 2006 +)
Medieval Jewish civilization: an encyclopedia. (Olin Reference DS124 .M386 2003 +)
Medieval England: An Encyclopedia. 1998.(Olin Reference DA 129 .M43x 1998) Articles vary in length but all are accompanied by bibliographies.
Medieval Ireland : an encyclopedia. 2005. (Olin Library Reference DA933 .M43 2005 +) Articles vary in length but all are accompanied by bibliographies.
Encyclopedia of barbarian Europe: society in transformation. 2003. (Olin Library Reference D135 .F73x 2003+)
Specialized Scholarly Subject Encyclopedias: Antiquity, the Bible, etc.
Oxford Classical Dictionary (5th edition)
Much more than a dictionary. An excellent source for sources on all aspects of the Classical World.
Encyclopedia of early Christianity c1997 Olin Library Reference (Non-Circulating) + BR162.2 .E56 1997
The Anchor Bible dictionary (Olin Library Reference BS440 .A53 1992) Much more than a dictionary. A multi-volume work on the Bible as primary source.
Oxford Reference: the Bible. This collection has a number of excellent encyclopedias and companions on the Bible
Encyclopaedia of Islam Excellent, but very challenging to use. Also in print at Olin Library Room 602 DS37.E56 1954+ Online version is more up to date, but doesn't include: glossary and index of technical terms; addenda and corrigenda.
Oxford Art Online provides web access to the entire text of The Dictionary of Art, ed. Jane Turner (1996, 34 vols.) and The Oxford Companion to Western Art, ed. Hugh Brigstocke (2001). Articles, and over 1,500 thumbnail art images and line drawings, extensive image links, and sophisticated search and navigation tools.
Routledge Encyclopedia of Philosophy. Excellent on all aspects of philosophy and history of ancient science.
The Oxford Companion to Classical Civilization. 1998. (Olin Reference DE5.O92x 1998+). A shortened version of The Oxford Classical Dictionary.
The Encyclopedia of Ancient Civilizations. New York: Mayflower Books, 1980. (Olin Reference CB 311 E565+)
Ancient Writers Greece and Rome. 1982 (Olin Reference PA 3002.A54) Grant, Michael, and Rachel Kitzinger. Civilization of the Ancient Mediterranean: Greece and Rome. 3 vols. New York: Scribners, 1988. (Olin Reference DE 59 C58 1988)
Sienkewicz, Thomas J. Encyclopedia of the Ancient World. 3 vols. Pasadena, CA: Salem Press, 2002. (Olin Reference CB311 .E54x 2002)
The Encyclopedia of Ancient Civilizations. 1980. (Olin Reference CB 311 E565+)
Civilization of the Ancient Mediterranean: Greece and Rome. 1988. (Olin Reference DE 59 C58 1988)
Encyclopedia of Greece and the Hellenic Tradition. 2000. (Olin Reference DF757.E53x 2000)