Jari Kreku Yang Qu Juha-Pekka Soininen Kari Tiensyrjä 223-229 2006 FDL http://www.ecsi-association.org/ecsi/main.asp?l1=library&fn=def&id=407 conf/fdl/2006 db/conf/fdl/fdl2006.html#KrekuQST06