Não informado. (1889). Bulletin of the Geological and Natural History Survey of Minnesota. Geological and Natural History Survey of Minnesota.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Bulletin of the Geological and Natural History Survey of Minnesota. Minneapolis, Minn: Geological and Natural History Survey of Minnesota, 1889.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Bulletin of the Geological and Natural History Survey of Minnesota. Geological and Natural History Survey of Minnesota, 1889.
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