Não informado. (2004). Environmental geology notes. Illinois State Geological Survey.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Environmental Geology Notes. Naperville, Ill: Illinois State Geological Survey, 2004.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Environmental Geology Notes. Illinois State Geological Survey, 2004.
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