Poczta, W., and M. Kołodziejczak. “Sozialökonomische Regionaldifferenzierung Der Landwirtschaft in Der Europäischen Union”. Journal of Agribusiness and Rural Development, Vol. 7, no. 1, Dec. 2008, pp. 123-40, http://www1.up.poznan.pl/jard/index.php/jard/article/view/856.