1. Investigation report for the current status of the sludge treatment in 2004;Japan Sewage Works Association,2007
2. Investigation report for the exhaust and treatment of the industrial waste in 2004;Ministry of the Environment,2007
3. Investigation report for battle against global warming on the sewage system field in 2004;Ministry of Land, Infrastructure and Transport Japan,2007
4. 2005–2007 NEDO report for developing a technology of high efficiency conversion of biomass energy;Sanki Engineering Co., Ltd., Tsukishima Kikai Co., Ltd., PWRI,2008
5. Influence of gas residence time and air ratio on the air gasification of dried sewage sludge in a bubbling fluidized bed;Manya;Fuel,2006