Warning - the bibtex entry below may be invalid: 
Missing 'booktitle' 
@conference{CPLPSBDS,
  author = "Karen Petrie with Barbara Smith and Neil Yorke-Smith",
  journal = "In Proc. STAIRS 2004",
  pages = "96-106",
  publisher = "IOS press",
  series = "Frontiers in Artificial Intelligence and Applications 109",
  title = "Dynamic Symmetry Breaking in Constraint Programming and Linear Programming Hybrids",
  url = "http://www.comp.leeds.ac.uk/bms/Papers/PetrieSTAIRS04.pdf",
  year = "2004",
}