Calvert, J. W. (1988). The Gibraltar: Socialism and labor in Butte, Montana, 1895-1920. Montana Historical Society Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रCalvert, Jerry W. The Gibraltar: Socialism and Labor in Butte, Montana, 1895-1920. Helena: Montana Historical Society Press, 1988.
एमएलए (8वां संस्करण) प्रशस्ति पत्रCalvert, Jerry W. The Gibraltar: Socialism and Labor in Butte, Montana, 1895-1920. Montana Historical Society Press, 1988.
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