1. V. G. Geptner, K. K. Chapskii, V. A. Arsen’ev, and V. E. Sokolov, Mammals of Soviet Union, Vol. 2, Part 3: Pinnipedia and Odontoceti (Vysshaya Shkola, Moscow, 1976) [in Russian].
2. Hydrometeorology and Hydrochemistry of Soviet Union, Vol. 2: The White Sea, No. 1: Hydrometeorological Conditions, Ed. by B. Kh. Glukhovskii and F. S. Terziev (Gidrometeoizdat, Leningrad, 1991) [in Russian].
3. S. V. Dorofeev, “Annual cycle of the harp seal in the White Sea,” in Soviet Fishery Studies in the Seas of European North (Nauka, Moscow, 1960), pp. 443–455.
4. I. I. Eliseeva and M. M. Yuzbashev, General Theory of Statistics (Finansy, Moscow, 2000) [in Russian].
5. L. R. Lukin and S. V. Snegovskoi, “Average long-term glaciation of the White Sea,” Meteorol. Gidrol., No. 4, 72–78 (1985).