Troeh, F. R., Donahue, R. L., & Hobbs, J. A. (1980). Soil and water conservation for productivity and environmental protection. Prentice-Hall.
Cita Chicago (17th ed.)Troeh, Frederick R., Roy L. Donahue, i J. Arthur Hobbs. Soil and Water Conservation for Productivity and Environmental Protection. Englewood Cliffs, N.J: Prentice-Hall, 1980.
Cita MLA (9th ed.)Troeh, Frederick R., et al. Soil and Water Conservation for Productivity and Environmental Protection. Prentice-Hall, 1980.
Atenció: Aquestes cites poden no estar 100% correctes.