Verbatim text: Gibson, A. C. and K. E. Horak. 1978. Systematic anatomy and phylogeny of Mexican columnar cacti. Ann. Missouri Bot. Gard. 65: 999–1057.
Author: Gibson, A.C., Horak, K.E.
Year: 1978
Title: Systematic anatomy and phylogeny of Mexican columnar cacti
Journal: Ann. Missouri Bot. Gard
Volume: 65
Pages: 999–1057
BHL link: http://www.biodiversitylibrary.org/part/13547