Ptak-Chmielewska, A. “BUSINESS DEMOGRAPHY ISSUES AND EMPIRICAL RESEARCH ON DYNAMICS OF ENTERPRISES’ POPULATION IN POLAND”. Acta Scientiarum Polonorum. Oeconomia, Vol. 10, no. 1, Mar. 2011, pp. 69-81, https://js.wne.sggw.pl/index.php/aspe/article/view/3998.