APA (7th ed.) Citation

Hasenohr, C., & Drobner, G. (1907). Ex = Libris Gustav Drobner.

Chicago Style (17th ed.) Citation

Hasenohr, Curt, and Gustav Drobner. Ex = Libris Gustav Drobner. [S.l, 1907.

MLA (9th ed.) Citation

Hasenohr, Curt, and Gustav Drobner. Ex = Libris Gustav Drobner. 1907.

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