@inproceedings{GroheKreSch05,
  title = "The Expressive Power of Two-Variable Least Fixed-Point Logics",
  author = "M. Grohe and S. Kreutzer and N. Schweikardt",
  year = "2005",
  booktitle = "Symposium on Mathematical Foundations of Computer Science (MFCS)",
  pages = "422 -- 434",
  publisher = "Springer",
  series = "Lecture Notes in Computer Science",
  url = "http://web.comlab.ox.ac.uk/oucl/work/stephan.kreutzer/Publications/05-mfcs.pdf",
}