APA (7th ed.) Citation

Knoll, J. H., & Siebert, H. (1967). Wilhelm von Humboldt. Intar Nationes.

Chicago Style (17th ed.) Citation

Knoll, Joachim H., and Horst Siebert. Wilhelm Von Humboldt. Bad Godesberg: Intar Nationes, 1967.

MLA (9th ed.) Citation

Knoll, Joachim H., and Horst Siebert. Wilhelm Von Humboldt. Intar Nationes, 1967.

Warning: These citations may not always be 100% accurate.