*Kaplan, Lucille, 1956, Tonal and Nagual in Coastal Oaxaca, "Journal of American Folklore 69":363–368*Nutini, Hugo G. & John M. Roberts.
* Kaplan, Lucille, 1956, Tonal and Nagual in Coastal Oaxaca, "Journal of American Folklore 69":363-368* Nutini, Hugo G. & John M. Roberts.