4Olmstead A L.Agricultural mechnization,productivity growth,and labor displacement. . 1989
5Farrington J,Martin A.Farmer participatory research:a review of concepts and practices. . 1987
6Nazarea V D.Cultural memory and biodiversity Tucson. . 1998
7Nrcus.Alternative agriculture. . 1989
8Saleem Shaik,Richard Perrin.Agricultural productivity and environmental impacts:the role of non-parametric analysis. American Agricultural Economics Association Meetings . 2001