Verbatim text: Chamberland, M. 1997. Systematics of the Echinocactus polycephalus complex (Cactaceae). Syst. Bot. 22: 303–313.
Author: Chamberland, M.
Year: 1997
Title: Systematics of the Echinocactus polycephalus complex (Cactaceae)
Journal: Syst. Bot
Volume: 22
Pages: 303–313