Não informado. (1914). Contributions from the Department of Botany. Pennsylvania State College, Department of Botany.
Chicago-referens (17:e uppl.)Não informado. Contributions from the Department of Botany. State College, Pa: Pennsylvania State College, Department of Botany, 1914.
MLA-referens (8:e uppl.)Não informado. Contributions from the Department of Botany. Pennsylvania State College, Department of Botany, 1914.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.