[1]J. Nowak и A. Frejowski, PMI, т. 170, вып. 2, сс. 228-231, апр. 2007.

[1]J. Nowak and A. Frejowski, “Mine waste management in upper silesian coal basin (USCB)”, PMI, vol. 170, no. 2, pp. 228-231, Apr. 2007.