Não informado. (1889). Bulletin of the Geological and Natural History Survey of Minnesota. Geological and Natural History Survey of Minnesota.
শিকাগো স্টাইল (17 তম সংস্করণ) উদ্ধৃতিNão informado. Bulletin of the Geological and Natural History Survey of Minnesota. Minneapolis, Minn: Geological and Natural History Survey of Minnesota, 1889.
M.L.A (8 ম সংস্করণ) উদ্ধৃতিNão informado. Bulletin of the Geological and Natural History Survey of Minnesota. Geological and Natural History Survey of Minnesota, 1889.
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