Não informado. (1933). Contributions from the Botanical Laboratory and the Morris Arboretum of the University of Pennsylvania. University of Pennsylvania.
Chicago (17e ed.) BronvermeldingNão informado. Contributions from the Botanical Laboratory and the Morris Arboretum of the University of Pennsylvania. Philadelphia, Pa: University of Pennsylvania, 1933.
MLA (8e ed.) BronvermeldingNão informado. Contributions from the Botanical Laboratory and the Morris Arboretum of the University of Pennsylvania. University of Pennsylvania, 1933.
Let op: Deze citaties zijn niet altijd 100% accuraat.