[1]C. Cyrnek и M. Sukiennik, PMI, т. 167, вып. 2, сс. 313-315, фев. 2006.

[1]C. Cyrnek and M. Sukiennik, “The elements of marketing in Polish subterranean building industry”, PMI, vol. 167, no. 2, pp. 313-315, Feb. 2006.