1. N.L. Segal, Entwined Lives: Twins and What They Tell us About Human Behavior, Plume, New York, 2000; J. Longman, The Trio to Rio, New York Times, June 3, 2016, p. SP1.
2. Twins in the World: The Legends They Inspire and the Lives They Lead;Piontelli,2008
3. A. White, The trouble with twins: Image and ritual of the Yorùbá ère ìbejì, 2010.
4. N.L. Segal, Art for twins: Yorùbá artists and their statues, Twin Res. Hum. Genet. 17(3) (2014) 215–221; F. Leroy, T. Olaleye-Oruene, G. Koeppen-Schomerus, E. Bryan, Yorùbá customs and beliefs pertaining to twins, Twin Res. 5(2) (2002) 132–136.
5. A.J. Bueltmann, White Queen of the Cannibals: The Story of Mary Slessor of Calabar, Literary Licensing, LLC, Whitefish, MT, 2011; Mary Slessor Foundation, Twins and Adopted Family, Available from: http://maryslessor.org/2014/04/her-adopted-family/