1. Gerhardt T. Thermische Behandlung von kommunalen Klärschlämmen in Kohlenstaubfeuerungen, in press.
2. Cenni R, Gerhardt T, Spliethoff H, Hein KRG. Ash quality and heavy metals behavior in combined combustion of bituminous coal and dried sewage sludge. 1997 International Conference on Incineration and Thermal Treatment Technologies, Oakland Marriott City Center, Oakland, (CA) 12–16 May 1997. p. 391.
3. Study of the combined combustion of municipal sewage sludge in coal dust furnaces;Gerhardt;VGB Kraftwerks technik (English issue),1996
4. Gerhardt T, Cenni R, Spliethoff H, Hein KRG. Combustion behaviour of coal-waste flames in pulverised fuel firing system. In Flame Measurement in a Pilot Scale Facility with Hard Coal and Dried Sewage Sludge, 22nd Int. Conf. on Coal Utilization & Fuel Systems Clearwater (FL), 17–20 March 1997. p. 389.
5. Cenni R, Gerhardt T, Risio B, Spliethoff H, Hein KRG. Effects of combined combustion of bituminous coal and dried sewage sludge on combustion behavior. Fourth International Conference on Clean Technologies and Combustion for a Clean Environment. Calouste Gulbenkian Foundation, Lisbon, Portugal, 7–10 July 1997. Session 32, p. 11.