Rapacz, A., P. Gryszel, and D. Jaremen. “THE VALLEY OF PALACES AND GARDENS AS AN EXAMPLE OF COOPERATION AT TOURISM MARKET”. Acta Scientiarum Polonorum. Oeconomia, vol. 9, no. 4, Dec. 2010, pp. 413-21, https://aspe.sggw.edu.pl/article/view/632.