Hanna Kozankiewicz Jacek Leszczylowski Kazimierz Subieta 381-399 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2798&spage=381 2003 conf/adbis/2003 ADBIS db/conf/adbis/adbis2003.html#KozankiewiczLS03