Não informado. (2004). Information Circular. Department of Natural Resources, Division of Geological Survey.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Information Circular. Columbus, Ohio: Department of Natural Resources, Division of Geological Survey, 2004.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Information Circular. Department of Natural Resources, Division of Geological Survey, 2004.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.