HARDING, K. C.; HÄRKÖNEN, T.; HELANDER, B.; KARLSSON, O. Status of Baltic grey seals: Population assessment and extinction risk. NAMMCO Scientific Publications, [S. l.], v. 6, p. 33–56, 2007. DOI: 10.7557/3.2720. Disponível em: https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2720. Acesso em: 21 sep. 2021.