Olsen, W. S. (2008). Hard air: Adventures from the edge of flying. University of Nebraska Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रOlsen, W. Scott. Hard Air: Adventures from the Edge of Flying. Lincoln: University of Nebraska Press, 2008.
एमएलए (8वां संस्करण) प्रशस्ति पत्रOlsen, W. Scott. Hard Air: Adventures from the Edge of Flying. University of Nebraska Press, 2008.
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