Não informado. (1891). Contributions from the Gray Herbarium of Harvard University. Harvard University.
Chicago-referens (17:e uppl.)Não informado. Contributions from the Gray Herbarium of Harvard University. Cambridge, Mass: Harvard University, 1891.
MLA-referens (8:e uppl.)Não informado. Contributions from the Gray Herbarium of Harvard University. Harvard University, 1891.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.