@inproceedings{MHK02,
         author = 	{R. Marelly and D. Harel and H. Kugler},
         title =  	{{Multiple Instances and Symbolic Variables in Executable Sequence Charts}},
         booktitle = 	{{Proc.\ 17th Ann. ACM Conf. on Object-Oriented Programming, Systems, 
                         Languages and Applications (OOPSLA'02), Seattle, WA}},
         year = 2002,
         NOTE = "To appear"
        }