APA (7th ed.) Citation

Kraze, H., & Würfel, W. (1965). Heimliche Briefe (o.A.). Union Verlag.

Chicago Style (17th ed.) Citation

Kraze, Hanna-Heide, and Wolfgang Würfel. Heimliche Briefe. o.A. Berlin: Union Verlag, 1965.

MLA (8th ed.) Citation

Kraze, Hanna-Heide, and Wolfgang Würfel. Heimliche Briefe. o.A. Union Verlag, 1965.

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