@inproceedings{ICALP-1974-Wijngaarden,
	author        = "Adriaan van Wijngaarden",
	booktitle     = "{Proceedings of the Second Colloquium on Automata, Languages and Programming}",
	doi           = "10.1007/3-540-06841-4_48",
	isbn          = "3-540-06841-4",
	pages         = "9--16",
	publisher     = "{Springer-Verlag}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{The Generative Power of Two-Level Grammars}",
	volume        = 14,
	year          = 1974,
}