Sipilä, Tero, and Heikki Hyvärinen. 1998. “Status and Biology of Saimaa (<i>Phoca Hispida saimensis</i>) and Ladoga (<i>Phoca Hispida ladogensis</I>) Ringed Seals”. NAMMCO Scientific Publications 1 (June):83-99. https://doi.org/10.7557/3.2982.