1. K.R.G. Hein, J.M. Bemtgen, EU Clean Coal Technology—Co-combustion of Coal and Biomass. Conference `Biomass Usage for Utility and Industrial Power,' April, 28–May 3, 1996, Snowbird, UT, USA.
2. J.M. Bemtgen, K.R.G. Hein, A. Minchener, Co-utilization of Coal, Biomass and Waste, Final Conference, Volume I: Summary of the Final Conference, 28–29 November 1994, Lisbon, ISBN-3-928123-14-9.
3. J.M. Bemtgen, K.R.G. Hein, A. Minchener, Combined Combustion of Biomass/Sewage Sludge and Coals, Volume II: Final Reports, EC-Research Project: APAS Contract COAL CT92-0002, ISBN-3-928123-16-5.
4. A. Kicherer: Untersuchungen zur Biomasseverbrennung in Staubfeuerungen.—Technische Moglichkeiten und Schadstofemissionen, PhD Thesis, Stuttgart, 1996.
5. T. Gerhardt, H. Spliethoff, K.R.G. Hein, Investigations on Co-combustion of Municipal Sewage Sludge in Pulverized Fuel Firing Systems, International Conference on Incineration and Thermal Treatment Technology, Savannah, GA, USA, May 1996.