Eswaran, H.; R. Lal; P.F. Reich (2001). "Land degradation: an overview". Responses to Land Degradation. Proc. 2nd. International Conference on Land Degradation and Desertification. New Delhi: Oxford Press. Archived from the original on 20 January 2012. Retrieved 5 February 2012.
Eswaran, H.; R. Lal; P.F. Reich (2001). "Land degradation: an overview". Responses to Land Degradation. Proc. 2nd. International Conference on Land Degradation and Desertification. New Delhi: Oxford Press. Archived from the original on 20 January 2012. Retrieved 5 February 2012.