APA (7th ed.) Citation

Bergman, B., Kicherer, B., & Johne, A. (1980). Katrin, streng geheim. Betz.

Chicago Style (17th ed.) Citation

Bergman, Birgitta, Birgitta Kicherer, and Arnhild Johne. Katrin, Streng Geheim. Wien, München: Betz, 1980.

MLA (9th ed.) Citation

Bergman, Birgitta, et al. Katrin, Streng Geheim. Betz, 1980.