Monjarás-Ruiz, J. (1979). Sobre Ted J. J. Leyenaar, Ulama - The perpetuation in Mexico of the Pre-Spanish ball game ullamaliztli. Historia Mexicana, 28(4), 622–624. Recuperado a partir de https://historiamexicana.colmex.mx/index.php/RHM/article/view/2721