^Ramsland, Katherine M.; McGrain, Patrick Norman (2010). Inside the Minds of Sexual Predators. ABC-CLIO. pp. 61–62. ISBN 0-313-37960-2
^Ågmo, Anders (2007). Functional and dysfunctional sexual behavior: a synthesis of neuroscience and comparative psychology. Academic Press. p. 454. ISBN 0-12-370590-8
^Swami, Viren; Furnham, Adrian (2008). The psychology of physical attraction. Routledge. p. 134. ISBN 0-415-42250-7