M. E. Morete, R. M. Pace, III, C. C. A. Martins, A. C. Freitas, and M. H. Engel, “Indexing seasonal abundance of humpback whales around Abrolhos Archipelago, Bahia, Brazil”, Lat. Am. J. Aquat. Mamm., vol. 2, no. 1, pp. 21-28, Jun. 2003.