Hadryjańska, Barbara. “Economic and Ecological Aspects of Utilization of Conventional and Renewable Energy Sources in Economic Processes”. Journal of Agribusiness and Rural Development 5, no. 377 (December 31, 2006): 142-160. Accessed April 20, 2024. http://www1.up.poznan.pl/jard/index.php/jard/article/view/983.