==References==*"National Audubon Society: Guide to Marine Mammals of the World" ISBN 0-375-41141-0*"Encyclopedia of Marine Mammals" ISBN 0-12-551340-2==External links==
* "National Audubon Society: Guide to Marine Mammals of the World" ISBN 0-375-41141-0* "Encyclopedia of Marine Mammals" ISBN 0-12-551340-2