Hiby, Lex, Torkel Lundberg, Olle Karlsson, John Watkins, Mart Jüssi, Ivar Jüssi, and Björn Helander. 2007. “Estimates of the size of the Baltic grey seal population based on photo-identification data”. NAMMCO Scientific Publications 6 (January). Tromsø, Norway:163-75. https://doi.org/10.7557/3.2731.