Hiby, Lex, Torkel Lundberg, Olle Karlsson, John Watkins, Mart Jüssi, Ivar Jüssi, and Björn Helander. “Estimates of the Size of the Baltic Grey Seal Population Based on Photo-Identification Data”. NAMMCO Scientific Publications 6 (January 1, 2007): 163–175. Accessed August 14, 2026. https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2731.