New York : Oxford University Press, 1995.
Extensive bibliography of historical literature. Several sections apply to medieval Europe.
Van Pelt Library Reference Desk: D20 .A55 1995

New York : Kraus reprint corp., 1964 [c1959].
Not so much a guide as a general bibliography of primary and secondary resources relevant to the study of the Middle Ages, 500-1300. The focus is on Western Europe but England is excluded.
Van Pelt Library: Z6203 .P19 1964

Millwood, N.Y. : Kraus International Publications, c1981.
Follows the same arrangement as Paetrow--focusing on Western Europe but excluing England--but coverage is extended to 1500. Supplements with information published after Paetrow was released in the 30s.
Van Pelt Reference: D117 .P29 1980 Suppl

New York : Garland Pub., 1987.
Includes a list of major letter collections.
Van Pelt Reference: D113 .B33 1987

New York : Garland Pub., 1983.
Extensive annotated bibliography of sources, secondary literature and reference material related to the middle ages.
Van Pelt Reference: CB351 .C76 1983

Toronto : University of Toronto Press, 1967-88.
A series of selective bibliographies, including works on liturgy, paleography, rhetoric, music, Chaucer and literature.
Do a title search for Toronto Medieval Bibliographies to see a list of titles in the series.