Freud, Sigmund (1916). Leonardo da Vinci: A PSYCHOSEXUAL STUDY OF AN INFANTILE REMINISCENCE. New York: MOFFAT YARD & COMPANY. pp. 39. Nuoroda tikrinta January 7, 2012. „The situation contained in the phantasy, that a vulture opened the mouth of the child and forcefully belabored it with its tail, corresponds to the idea of fellatio, a sexual act in which the member is placed into the mouth of the woman.“
Robert Crooks, Karla Baur (2010). „Our Sexuality [Mūsų seksualumas].“ (anglų k.) Cengage Learning. p. 241. ISBN 978-0-495-81294-4. Suarchyvuotas originalas 2021-03-10. Nuoroda tikrinta 2013-09-12. Felacija yra oralinė varpos ir kapšelio stimuliacija.
Nilamadhab Kar, Gopal Chandra Kar (2005). „Comprehensive Textbook of Sexual Medicine [Išsamus seksualinės medicinos vadovas].“ (anglų k.). Jaypee Brothers Publishers. p. 106. ISBN 978-81-8061-405-7. Suarchyvuotas originalas 2016-12-28. Nuoroda tikrinta 2013-09-12.