Warning - the bibtex entry below may be invalid: 
Missing 'booktitle' 
@conference{PODS2007,
  author = "G. Gottlob, Z. Miklos, T. Schwentick",
  journal = "Journal of the ACM",
  title = "Generalized hypertree decompositions: NP-hardness and tractable variants",
  year = "to appear",
}