01128nam a2200229Ia 4500 CTU_219225 210402s9999 xx 000 0 und d 333.8 N277 United Nations Department of Economic and Social Affairs Mineral resources development with particular reference to the developing countries : Department of Economic and Social Affairs United Nations. Department of Economic and Social Affairs New York United Nations 1970 For the purpose of this report, the tern "mineral resources", meaning natural mineral concentrations capable of exploitation, will embrace both mineable products, notaby metallic minerals, minerals used in the chemical and quarried products such as cement and construction materials, clays, sands and gravels. Mỏ và tài nguyên khoáng sản,Mines and mineral resources Phát triển quốc gia,Developing countries Trúc Trung tâm Học liệu Trường Đại học Cần Thơ