Monjarás-Ruiz, Jesús. «Sobre Ted J. J. Leyenaar, Ulama - The Perpetuation in Mexico of the Pre-Spanish Ball Game Ullamaliztli». Historia Mexicana 28, no. 4 (abril 1, 1979): 622–624. Accedido mayo 6, 2024. https://historiamexicana.colmex.mx/index.php/RHM/article/view/2721.