Biographical material on the two composers and their relationship with each other. Includes sample music in MIDI audio format.

Biographical material, musicological study, and link to discussion of organum polyphony.

Speculation about his person and his place in medieval music from the Grove Concise Dictionary of Music entry at WQXR radio.

Wikipedia article including information about the Magnus Liber and polyphonic organum with internal references to related people and topics and bibliographic material.

Biography, major works and influence, and links to information on medieval polyphony.

Biographical data, bibliography, major works, influences on Western music, and links.

Biographical timeline, suggested reading, key works, and recommended recordings from Humanities Web.