Pepliński, Benedykt, Karol Wajszczuk, and Dariusz Majchrzycki. 2002. “The Labour Inputs Analysis in Developing Farms in Their Gross Supply Aspect”. Journal of Agribusiness and Rural Development 1 (343), 137-46. http://www1.up.poznan.pl/jard/index.php/jard/article/view/1073.