Cita APA (7th ed.)
Zimmermann, G. Zimmermann, Gerhard.
Cita Chicago (17th ed.)
Zimmermann, Gerhard. Zimmermann, Gerhard.
Cita MLA (9th ed.)
Zimmermann, Gerhard. Zimmermann, Gerhard.
Atenció: Aquestes cites poden no estar 100% correctes.