CLARK II, E. H., HAVERKAMP, J. A., & CHAPMAN, W. (1985). Eroding soils: The off-farm impacts. Th Conservation Foundation.
Lua i Stíl Chicago (17ú heag.)CLARK II, Edwin H., Jenniver A. HAVERKAMP, agus William CHAPMAN. Eroding Soils: The Off-farm Impacts. Washington: Th Conservation Foundation, 1985.
Lua MLA (9ú heag.)CLARK II, Edwin H., et al. Eroding Soils: The Off-farm Impacts. Th Conservation Foundation, 1985.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.