Não informado. (1933). Contributions from the Botanical Laboratory and the Morris Arboretum of the University of Pennsylvania. University of Pennsylvania.
Chicago Style (17. basım) AtıfNão informado. Contributions from the Botanical Laboratory and the Morris Arboretum of the University of Pennsylvania. Philadelphia, Pa: University of Pennsylvania, 1933.
MLA (8th ed.) AtıfNão informado. Contributions from the Botanical Laboratory and the Morris Arboretum of the University of Pennsylvania. University of Pennsylvania, 1933.
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