Pomianek, I. “SOCIO-ECONOMIC DEVELOPMENT LEVEL OF RURAL AREAS OF WARMIA AND MAZURY PROVINCE”. Acta Scientiarum Polonorum. Oeconomia, Vol. 9, no. 3, Sept. 2010, pp. 227-39, https://js.wne.sggw.pl/index.php/aspe/article/view/3923.