APA (7th ed.) Citation

Staeger, F., Spitz, H., & Spitz, M. (1937). Ex Libris Mitzi u. Hugo Spitz.

Chicago Style (17th ed.) Citation

Staeger, Ferdinand, Hugo Spitz, and Mitzi Spitz. Ex Libris Mitzi U. Hugo Spitz. 1937.

MLA (9th ed.) Citation

Staeger, Ferdinand, et al. Ex Libris Mitzi U. Hugo Spitz. 1937.