Não informado. (1999). Minnesota botanical studies. Geological and Natural History Survey of Minnesota.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Minnesota Botanical Studies. Minneapolis, Minn: Geological and Natural History Survey of Minnesota, 1999.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Minnesota Botanical Studies. Geological and Natural History Survey of Minnesota, 1999.
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