Knutson, R. D., Penn, J. B., & Flinchbaugh, B. L. (1998). Agricultural and food policy (4th ed.). Prentice Hall.
Dyfyniad Arddull ChicagoKnutson, Ronald D., J. B. Penn, and Barry L. Flinchbaugh. Agricultural and Food Policy. 4th ed. Upper Saddle River, N.J: Prentice Hall, 1998.
Dyfyniad MLAKnutson, Ronald D., et al. Agricultural and Food Policy. 4th ed. Prentice Hall, 1998.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.