Panova E, Agafonov A, Belikov R, Melnikova F. Vocalizations of captive beluga whales, Delphinapterus leucas: Additional evidence for contact signature ?mixed? calls in belugas. Marine Mammal Science. 2017;33(3):889 - 903. Available at: http://doi.wiley.com/10.1111/mms.2017.33.issue-3.