Não informado. (2018). Special Publication. University of Kentucky, Kentucky Geological Survey.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Special Publication. Lexington, Ky: University of Kentucky, Kentucky Geological Survey, 2018.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Special Publication. University of Kentucky, Kentucky Geological Survey, 2018.
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