Gabrys. Program Earth. University of Minnesota Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रGabrys. Program Earth. University of Minnesota Press.
एमएलए (9वां संस्करण) प्रशस्ति पत्रGabrys. Program Earth. University of Minnesota Press.
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