den Biggelaar, C., R. Lal, R.K. Wiebe, H. Eswaran, V. Breneman, and P. Reich. 2004. The global impact of soil erosion on productivity. II: Effects on crop yields and production over time. Advances in Agronomy, vol. 81: 49–95.

Doran, J.W., M. Sarrantonio, and M.A. Liebig. 1996. Soil health and sustainability. In Advances in Agronomy, vol. 56, pp. 1–54. San Diego, CA: Academic Press, Inc.

Graham, R.D., R.M. Welch, D.A. Saunders, I. Ortiz-Monasterio, H.E. Bouis, M. Bonierbale, S. de Haan, G. Burgos, G. Thiele, R. Liria, C.A. Meisner, S.E. Beebe, M.J. Potts, M. Kadian, P.R. Hobbs, R.K. Gupta, and S. Twomlow. 2007. Nutritious subsistence food systems. In Advances in Agronomy, vol. 92, pp. 1–74. San Diego, CA: Academic Press, Inc.

Hillel, D. 1991. Out of the Earth: Civilization and the Life of the Soil. Berkeley: University of California Press.

Spillman, W.J. 1906. Renovation of Worn-out Soils. Farmers’ Bulletin No. 245. Washington, DC: USDA; Government Printing Office.

Topp, G.C., K.C. Wires, D.A. Angers, M.R. Carter, J.L.B. Culley, D.A. Holmstrom, B.D. Kay, G.P. Lafond, D.R. Langille, R.A. McBride, G.T. Patterson, E. Perfect, V. Rasiah, A.V. Rodd, and K.T. Webb. 1995. Changes in soil structure. In The Health of Our Soils: Toward Sustainable Agriculture in Canada, ed. D.F.   Acton and L.J. Gregorich, chapter 6. Centre for Land and Biological Resources Research. Research Branch, Agriculture and Agri-Food Canada. Publication 1906/E.