“Historical Ecology and Future Explorations” in “Amazonian Dark Earths: origin, properties, and management” by J. Lehmann, N. Kaampf, W.I. Woods, W. Sombroek, D.C. Kern, T.J.F. Cunha et al., Chapter 23, 2003. (Clark Erickson), p. 484
“Discovery and awareness of anthropogenic amazonian dark earths (terra preta)”, by William M. Denevan, University of Wisconsin–Madison, and William I. Woods, University of Kansas.
