Snyman, H. A. . “A Case Study on in Situ Rooting Profiles and Water-Use Efficiency of Cactus Pears, Opuntia Ficus-Indica and O. Robusta”. Journal of the Professional Association for Cactus Development, vol. 7, Jan. 2006, pp. 1-21, doi:10.56890/jpacd.v7i.284.