[Zimmerman A. D., Parfitt B. D., Ferocactus, Flora of North America North of Mexico, Oxford University Press, New York, Oxford, 2003b, tom 4]
A floristic treatment of the genus with a key and descriptions of stems, spines, flowers, fruits, seeds and habitats. The descriptions of F. wislizeni and F. cylindraceus that were read allow comparison of diagnostic traits of the two species. Current accepted names were checked separately in POWO.