Binderman, Z., B. Borkowski, and W. Szczesny. “REGIONAL DIFFERENTIATION OF POLISH TOURISM ECONOMY WITHIN 2002–2008”. Acta Scientiarum Polonorum. Oeconomia, vol. 9, no. 4, Dec. 2010, pp. 71-82, https://aspe.sggw.edu.pl/article/view/663.