APA (7th ed.) Citation

Nietzsche, F. W., & Leidecker, K. F. (1959). Unpublished letters. Philosophical Library.

Chicago Style (17th ed.) Citation

Nietzsche, Friedrich Wilhelm, and Kurt F. Leidecker. Unpublished Letters. New York: Philosophical Library, 1959.

MLA (9th ed.) Citation

Nietzsche, Friedrich Wilhelm, and Kurt F. Leidecker. Unpublished Letters. Philosophical Library, 1959.