books.google.cz - Behavioural observations from both the field and captivity indicate that same-sex sexual interactions are widespread throughout the animal kingdom, and occur quite frequently in certain non-human species. Proximate studies of these phenomena have yielded important insights into genetic, hormonal and...http://books.google.cz/books/about/Homosexual_Behaviour_in_Animals.html?id=KXM3F59y1jkC&utm_source=gb-gplus-shareHomosexual Behaviour in Animals
