Não informado. (1892). Contributions from the Botanical Laboratory of the University of Pennsylvania. University of Pennsylvania.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Contributions from the Botanical Laboratory of the University of Pennsylvania. Philadelphia, Pa: University of Pennsylvania, 1892.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Contributions from the Botanical Laboratory of the University of Pennsylvania. University of Pennsylvania, 1892.
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