1。Farm size and productivity in Malawian smallholder agriculture
Andrew Dorward
Journal of Development Studies, 1743-9140, Volume 35, Issue 5, 1999, Pages 141 – 161
http://www.informaworld.com/smpp/ftinterface?content=a787117115&rt=0&format=pdf
2。Does Intensification Improve the Economic Efficiency of Dairy Farms?
Alvarez et al. J. Dairy Sci..2008; 91: 3693-3698
http://www.dairy-science.org/cgi/reprint/91/9/3693
3。Farmers' Perception of Sustainability for Crop Production on the North China Plain
Y. P. Wei;  R. E. White;  D. Chen;  B. A. Davidson; J. B. Zhang
Journal of Sustainable Agriculture, 1540-7578, Volume 30, Issue 3, 2007, Pages 129 – 147
http://www.informaworld.com/smpp/ftinterface?content=a904332787&rt=0&format=pdf

4。Impediments to the Diversification of Rural Economies in Central and Eastern Europe: Evidence from Small-scale Farms in Poland
Hannah Chaplin;  Matthew Gorton; Sophia Davidova
Regional Studies, 1360-0591, Volume 41, Issue 3, First published 2007, Pages 361 – 376
http://www.informaworld.com/smpp/ftinterface?content=a779607698&rt=0&format=pdf