Knopf's commentary on the Didache and 1-2 Clement was originally entitled Die Apostolischen Vater. Band 1: Die Lehre der zwolf Apostel. Die zwei Clemensbriefe and was published in the Handbuch zum Neuen Testament. Erganzung-band in 1920. The volume contains introductory information for the Didache and 1-2 Clement, a translation of these texts, and accompanying critical commentary which proceeds verse by verse.