Soil conservation as a goal among farmers: Results of a survey and cluster analysis Steven E. Kraft, Paul L. Roth, and Angela C. Thielen Journal of Soil and Water Conservation September 1989 vol. 44 no. 5 487-490 http://www.jswconline.org/content/44/5/487.abstract

请设置出售帖，我来买，谢谢。。

贴了两天了也没人应助，郁闷阿