Verbatim text: Heiser, C. B., D. M. Smith, S. Clevenger, and W. C. Martin. 1969. The North American sunflowers (Helianthus). Mem. Torrey Bot. Club 22(3).
Author: Heiser, C.B., Smith, D.M., Clevenger, S., Martin, W.C.
Year: 1969
Title: The North American sunflowers (Helianthus)
Journal: Mem. Torrey Bot. Club
Volume: 22