Contributions from the Botanical Laboratory and the Morris Arboretum of the University of Pennsylvania - University of Pennsylvania. Botanical Laboratory. ([s.n, 1934)

Contributions from the United States National Herbarium - United States. National Herbarium. (Smithsonian Institution Press, 1906)

Flora of the state of Washington - Piper, Charles V. (Charles Vancouver), 1867 -1926 (G.P.O, 1906)

Flora of the state of Washington - Piper, Charles V. (Charles Vancouver), 1867 -1926 (Govt. Print. Off, 1906)