APA (7th ed.) Citation
Frey, K., & Achtenhagen, F. (1975). Curriculum-Handbuch. Piper.
Chicago Style (17th ed.) Citation
Frey, Karl, and Frank Achtenhagen. Curriculum-Handbuch. München, Zürich: Piper, 1975.
MLA (9th ed.) Citation
Frey, Karl, and Frank Achtenhagen. Curriculum-Handbuch. Piper, 1975.
Warning: These citations may not always be 100% accurate.