Simpson. River City and Valley Life. University of Pittsburgh Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रSimpson. River City and Valley Life. University of Pittsburgh Press.
एमएलए (9वां संस्करण) प्रशस्ति पत्रSimpson. River City and Valley Life. University of Pittsburgh Press.
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