Borówka , B. (2009). Classification and protection of hard coal deposit resources in Poland. Записки Горного института, 181, 14-16. извлечено от https://pmi.spmi.ru/pmi/article/view/7012

Borówka , B. (2009). Classification and protection of hard coal deposit resources in Poland. Journal of Mining Institute, 181, 14-16. Retrieved from https://pmi.spmi.ru/pmi/article/view/7012