1. 1)Raask, E., Mineral Impurities in Coal Combustion, (Hemisphere Publishing Corporation), p. 169, P. 189(1985)
2. 2)Laursen, K., Frandsen, F. J., Larsen, O. H., Impact of mineral impurities in solid fuel combustion, p. 357-366(1999)
3. 6)Huang, L. Y., Norman, J. S., Poukashanian, M., Williams, A., Fuel, 75, 3(1996)
4. 7)Valero, A., Cortes, C., Prog. Energy. Combust. Sci., 22, 2(1996)
5. 8)Naruse, I., Kamihashira, D., Khairil, Miyauchi, Y., Kato, Y., Yamashita, T., Tominaga, H., Fuel, 84, 405-410(2005)