APA (7th ed.) Citation

Widén, C., Sarvela, J., & Ahti, T. (1967). The Dryopteris Spinulosa Complex in Finland. Soc. pro Fauna et Flora Fennica.

Chicago Style (17th ed.) Citation

Widén, Carl-Johan, Jaakko Sarvela, and Teuvo Ahti. The Dryopteris Spinulosa Complex in Finland. Helsinki: Soc. pro Fauna et Flora Fennica, 1967.

MLA (9th ed.) Citation

Widén, Carl-Johan, et al. The Dryopteris Spinulosa Complex in Finland. Soc. pro Fauna et Flora Fennica, 1967.