1. Slijper, E.J., “Whales,” Hutchinson, London, 1962.
2. Matthews, L.H., Editor, “The Whale,” George Allen and Unwin Ltd., London, 1968.
3. Norris, K.S., in “The Biology of Marine Mammals,” Edited by H.T. Anderson, Academic Press, New York, 1969, p. 391–423.
4. Evans, W.E., in “Marine Bio-acoustics,” Vol. 2, Edited by W.N. Tavolga, New York, 1967, p. 159–186.
5. Norris, K.S., and W.E. Evans, Ibid. in “Marine Bio-acoustics,” Vol. 2, Edited by W.N. Tavolga, New York, 1967, p. 305–316.