Não informado. (1892). Contributions from the Botanical Laboratory of the University of Pennsylvania. University of Pennsylvania.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Contributions from the Botanical Laboratory of the University of Pennsylvania. Philadelphia, Pa: University of Pennsylvania, 1892.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Contributions from the Botanical Laboratory of the University of Pennsylvania. University of Pennsylvania, 1892.
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