Attributes / relations provided by
♦ ¹del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.
♦ ²Summer Diet of the Harbour Porpoise (Phocoena phocoena) in the Estuary and the Northern Gulf of St. Lawrence, Pierre-Michel Fontaine, Mike O. Hammill, Cyrille Barrette, and Michael C. Kingsley, Can. J. Fish. Aquat. Sci. 51(1): 172–178 (1994)