Christina Richards, Meg Barker: Sexuality and Gender for Mental Health Professionals: A Practical Guide. SAGE, 2013, ISBN 1-4462-9313-0, S.124–127 (englisch, google.com [abgerufen am 3. Juli 2014]).
Karli June Cerankowski, Megan Milks: Asexualities: Feminist and Queer Perspectives. Routledge, 2014, ISBN 1-134-69253-6, S.89–93 (google.com [abgerufen am 3. Juli 2014]).
Janet Shibley Hyde, John D. DeLamater, E. Sandra Byers: Understanding Human Sexuality. McGraw-Hill Ryerson, 2009, ISBN 978-0-07-803539-5, S.431: „A person's erotic and emotional orientation toward members of his or her own gender or members of the other gender.“[1]