STEPAN, J. THE IMPACT OF COPPER PRICE VARIATION ON THE ECONOMIC EFFICIENCY AND ENVIRONMENTAL SUSTAINABILITY OF KGHM OPERATIONS. Economics and Environment, [S. l.], v. 59, n. 4, p. 14, 2016. Disponível em: https://www.ekonomiaisrodowisko.pl/journal/article/view/211. Acesso em: 1 may. 2024.