Banov , M., P. Ivanov, V. Tsolova, J. Bech, M. Zhyianski, and M. Blagiev. 2014. “RESOLVING OF ENVIRONMENTAL PROBLEMS CAUSED BY THE PROCESSING OF COPPER ORE”. Bulgarian Journal of Agricultural Science 20 (3): 581-89. https://agriacad.eu/ojs/index.php/bjas/article/view/6262.