APA (7th ed.) Citation

Leppäkoski, E., Gollasch, S., & Olenin, S. (2002). Alien species in European waters.

Chicago Style (17th ed.) Citation

Leppäkoski, Erkki, Stephan Gollasch, and Sergej Olenin. Alien Species in European Waters. 2002.

MLA (8th ed.) Citation

Leppäkoski, Erkki, et al. Alien Species in European Waters. 2002.