Tontz, R. L. (1966). Foreign agricultural trade: Selected readings ([1st ed.].). Iowa State University Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रTontz, Robert L. Foreign Agricultural Trade: Selected Readings. [1st ed.]. Ames: Iowa State University Press, 1966.
एमएलए (9वां संस्करण) प्रशस्ति पत्रTontz, Robert L. Foreign Agricultural Trade: Selected Readings. [1st ed.]. Iowa State University Press, 1966.