Musicologist, best known for his historical series
Organum (1920-1960)
He was also one of the many editors of the monumental
Denkmäler deutscher Tonkunst, founded by
Philipp Spitta (1841—1894) in 1892. There were two series, first 65 volumes, 1892-1931 and second 38 volumes, 1900-1938.