Hansen, J. R. (2014). A difficult par: Robert Trent Jones Sr. and the making of modern golf. Gotham Books.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रHansen, James R. A Difficult Par: Robert Trent Jones Sr. and the Making of Modern Golf. New York: Gotham Books, 2014.
एमएलए (8वां संस्करण) प्रशस्ति पत्रHansen, James R. A Difficult Par: Robert Trent Jones Sr. and the Making of Modern Golf. Gotham Books, 2014.
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