1. D. Ferry, Transl., The Georgics of Virgil (Farrar, Straus and Giroux, 2004).
2. G. P. Marsh, Man and Nature (Scribner, 1864).
3. E. B. Balfour, The Living Soil (Faber and Faber, 1943).
4. H. H. Bennett, Our American Land (US Department of Agriculture, 1946).
5. S. W. Trimble, Man-Induced Soil Erosion on the Southern Piedmont (Soil and Water Conservation Society, 1974).