Brown, M. 1996. Organic Farming Research Foundation Information Bulletin. Brown, M. 1996. Dig deep to make your garden bloom. Brown, M and J. Leap.
Mechanical cultivation saves small-scale growers time and money.
Gliessman, S.R. 1997. Ecological Processes in Sustainable Agriculture. Inc. Gliessman, S.R. 1996. University of California. Gliessman, S.R. 1996.