Tiznado-Hernández, Martín E., Judith Fortiz-Hernández, Ángel J. Ojeda-Contreras, and Armida Rodríguez-Félix. “Use of the Elliptical Mathematical Formula to Estimate the Surface Area of Cladodes in Four Varieties of Opuntia Ficus-Indica”. Journal of the Professional Association for Cactus Development 12 (April 23, 2010): 98–109. Accessed October 24, 2025. https://jpacd.org/jpacd/article/view/101.