1. Eurostat Yearbook '95. A statistical eye on Europe (1983–1993). Eurostat, the Statistical Office of the European Community, 1995.
2. Clarke LB. Application for coal-use residues. Int En Ag (IEA) Coal Research, 1992.
3. Tyson SS, Blackstock TH, Jr. Overview of coal ash use in construction and related applications. In: American Coal Ash Association, Proceedings of the Industrial Waste Conference, January 1995, Southern, FL 1995;49:635–641.
4. Kunz P. Major aspects of the utilization of hard-coal fly ash in construction. In: Proceedings of the 4th International Recycling Congress, Berlin, Germany. Berlin: EF-Verlag Energ Umwelttech, 1984:854–859.
5. Bituminous coal fly ash. A filler for asphalt highway construction;Boehm;VGB Kraftwerkstech,1996