Troeh, F. R., Donahue, R. L., & Hobbs, J. A. (1980). Soil and water conservation for productivity and environmental protection. Prentice-Hall.
Dyfyniad Arddull ChicagoTroeh, Frederick R., Roy L. Donahue, and J. Arthur Hobbs. Soil and Water Conservation for Productivity and Environmental Protection. Englewood Cliffs, N.J: Prentice-Hall, 1980.
Dyfyniad MLATroeh, Frederick R., et al. Soil and Water Conservation for Productivity and Environmental Protection. Prentice-Hall, 1980.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.