Ojo, J.R. (1978). "The symbolism and significance of Epa-type masquerade headpieces". Man. New Series. 13 (457470): 455–470. doi:10.2307/2801941. JSTOR2801941.
Akintoye, S. A. (1969). "The North-Eastern Yoruba Districts and the Benin Kingdom". Journal of the Historical Society of Nigeria. 4 (4): 539–553. JSTOR41856778.
Ojo, J.R. (1978). "The symbolism and significance of Epa-type masquerade headpieces". Man. New Series. 13 (457470): 455–470. doi:10.2307/2801941. JSTOR2801941.