APA (7th ed.) Citation

Spuler, A., & Hofmann, E. (1989). Der Schmetterlinge Europas. Apollo Books.

Chicago Style (17th ed.) Citation

Spuler, Arnold, and Ernst Hofmann. Der Schmetterlinge Europas. Svendborg: Apollo Books, 1989.

MLA (9th ed.) Citation

Spuler, Arnold, and Ernst Hofmann. Der Schmetterlinge Europas. Apollo Books, 1989.