@InProceedings{	  dl02stacs,
  author	= "Volker Diekert and Markus Lohrey",
  booktitle	= "Proc. 19th Annual Symposium on Theoretical Aspects of
		  Computer Science (STACS'02), Juan les Pin (France), 2002",
  pages		= "501--512",
  editor	= "H. Alt and A. Ferreira",
  series	= "Lecture Notes in Computer Science",
  volume	= "2285",
  publisher	= "Springer-Verlag",
  year		= "2002",
  title		= "Existential and Positive Theories of Equations in Graph
		  Products",
  doi		= "10.1007/3-540-45841-7_41"
}