Maciej Gawinecki Zygmunt Vetulani Minor Gordon Marcin Paprzycki Representing Users in a Travel Support System. 393-399 2005 conf/isda/2005 ISDA http://doi.ieeecomputersociety.org/10.1109/ISDA.2005.80 db/conf/isda/isda2005.html#GawineckiVGP05