Não informado. (1914). Contributions from the Department of Botany. Pennsylvania State College, Department of Botany.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Contributions from the Department of Botany. State College, Pa: Pennsylvania State College, Department of Botany, 1914.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Contributions from the Department of Botany. Pennsylvania State College, Department of Botany, 1914.
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