@inproceedings{ICALP-1997-Wilke,
	author        = "Thomas Wilke",
	booktitle     = "{Proceedings of the 24th International Colloquium on Automata, Languages and Programming}",
	doi           = "10.1007/3-540-63165-8_191",
	isbn          = "3-540-63165-8",
	pages         = "347--357",
	publisher     = "{Springer-Verlag}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{Star-Free Picture Expressions are Strictly Weaker Than First-Order Logic}",
	volume        = 1256,
	year          = 1997,
}