• Peter Buneman, Susan Davidson, Gerd Hillebrand, Dan Suciu,
  A query language and optimization techniques for unstructured data
  In Proceedings of ACM-SIGMOD International Conference on Management of Data, pp. 505-516, 1996
  
• Peter Buneman, Susan Davidson, Gerd Hillebrand, Dan Suciu,
  A query language and optimization techniques for unstructured data
  University of Pennsylvania, Computer and Information Science Department, Technical Report, 96-09, 1996