APA (7th ed.) Citation

Hardtmut, A. (1940). Schule der Philatelie (1.-20. Taus.). Heering.

Chicago Style (17th ed.) Citation

Hardtmut, Alexander. Schule Der Philatelie. 1.-20. Taus. Harzburg: Heering, 1940.

MLA (9th ed.) Citation

Hardtmut, Alexander. Schule Der Philatelie. 1.-20. Taus. Heering, 1940.

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