Não informado. (1925). Information Circular. U.S. Department of the Interior, Bureau of Mines.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Information Circular. Washington: U.S. Department of the Interior, Bureau of Mines, 1925.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Information Circular. U.S. Department of the Interior, Bureau of Mines, 1925.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.