Não informado. (1999). Minnesota botanical studies. Geological and Natural History Survey of Minnesota.
Chicago-Zitierstil (17. Ausg.)Não informado. Minnesota Botanical Studies. Minneapolis, Minn: Geological and Natural History Survey of Minnesota, 1999.
MLA-Zitierstil (8. Ausg.)Não informado. Minnesota Botanical Studies. Geological and Natural History Survey of Minnesota, 1999.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.