Willi Apel, "The Notation of Polyphonic Music, 900-1600"

A book on musical notation that deals exclusively and thoroughly with the notation forms of polyphonic music prior to 1600.

Willi Apel taught at Harvard University from 1938 to 1942, and for twenty years at Indiana University from 1950-1970. His work included the "Harvard Dictionary of Music" (1944) and the "Historical Anthology of Music," , co-authored with Archibald Thompson Davison (1949).