Developments in language theory : 7th International Conference, DLT 2003, Szeged, Hungary, July 7-11, 2003 : proceedings - Conference on Developments in Language Theory 2003 : Szeged, Maďarsko); Èsik, Zoltán, 1951-; Fülöp, Zoltán, 1955- (Berlin : Springer, 2003)