@inproceedings{SKS00,
	author	    =	"S. Shamir and O. Kupferman and E. Shamir",
	title	    =   "Branching-depth hierarchies",
        booktitle   =	"Proc. 7th international workshop in
                  expressiveness in concurrency", 
        series   =   "Electronic Notes in Theoretical Computer
                  Science", 
	year	    =	"2000"
}