Verbatim text: Fernald, M. L. and K. M. Wiegand. 1915. The genus Euphrasia in North America. Rhodora 17: 181–201.
Author: Fernald, M.L., Wiegand, K.M.
Year: 1915
Title: The genus Euphrasia in North America
Journal: Rhodora
Volume: 17
Pages: 181–201