Verbatim text: Ball, P. W. and V. H. Heywood. 1964. A revision of the genus Petrorhagia. Bull. Brit. Mus. (Nat. Hist.), Bot. 3: 121–172.
Author: Ball, P.W., Heywood, V.H.
Year: 1964
Title: A revision of the genus Petrorhagia
Journal: Bull. Brit. Mus. (Nat. Hist.), Bot
Volume: 3
Pages: 121–172