1. Sludge management of small water and wastewater treatment plants
2. CEC. 2000. “Working Document on Sludge (3rd Draft), ENV.E.3/LM, 27 April 2000”. Brussels, Belgium: Commission of the European Communities. (http://europa.eu.int/comm/environment/sludge/sludge_en.pdf.)
3. Zessner, M. and Kroiss, H. 1999. Problems with Balancing Nutrients in the Hydrosphere. Proc., CD-ROM, to the 28th IAHR congress—Hydraulic Engineering for Sustainable Water Resource Management. Aug.22–271999, Graz, Austria.
4. Benchmarking of municipal waste water treatment plants (an Austrian project)