Cita APA (7a ed.)

Krzywka, R., & Fogedgaard, H. (1960). Ex Libris Helmer Fogedgaard.

Cita Chicago Style (17a ed.)

Krzywka, Ryszard, y Helmer Fogedgaard. Ex Libris Helmer Fogedgaard. [S.l, 1960.

Cita MLA (9a ed.)

Krzywka, Ryszard, y Helmer Fogedgaard. Ex Libris Helmer Fogedgaard. 1960.