@InProceedings(cw99,
  author =       "Stephen Clark and David Weir",
  title =        "An Iterative Approach to Estimating Frequencies over a 
                  Semantic Hierarchy", 
  booktitle =   "Proceedings of the Joint SIGDAT Conference on Empirical 
                   Methods in Natural Language Processing and Very Large 
                   Corpora",
 pages = {258-265},
  year =      1999)