Verbatim text: Perdue, R. E. Jr. 1957. Synopsis of Rudbeckia subgenus Rudbeckia. Rhodora 59: 293–299.
Author: Perdue, R.E.
Year: 1957
Title: Synopsis of Rudbeckia subgenus Rudbeckia
Journal: Rhodora
Volume: 59
Pages: 293–299