Não informado. (1892). Contributions from the Botanical Laboratory of the University of Pennsylvania. University of Pennsylvania.
Chicago-viite (17. p.)Não informado. Contributions from the Botanical Laboratory of the University of Pennsylvania. Philadelphia, Pa: University of Pennsylvania, 1892.
MLA-viite (8. p.)Não informado. Contributions from the Botanical Laboratory of the University of Pennsylvania. University of Pennsylvania, 1892.
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