Tiznado-Hernández, M. E., Fortiz-Hernández, J., Ojeda-Contreras, Ángel J. and Rodríguez-Félix, A. (2010) “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, pp. 98–109. doi: 10.56890/jpacd.v12i.101.