SIPILÄ, Tero; HYVÄRINEN, Heikki. Status and biology of Saimaa (Phoca hispida saimensis) and Ladoga (Phoca hispida ladogensis) ringed seals. NAMMCO Scientific Publications, Tromsø, Norway, v. 1, p. 83–99, 1998. DOI: 10.7557/3.2982. Disponível em: https://septentrio.uit.no/index.php/NAMMCOSP/article/view/2982. Acesso em: 4 jun. 2026.