@InProceedings{gatt-portet:2011:ENLG,
  author    = {Gatt, Albert  and  Portet, Fran\c{c}ois},
  title     = {If it may have happened before, it happened, but not necessarily before},
  booktitle = {Proceedings of the 13th European Workshop on Natural Language Generation},
  month     = {September},
  year      = {2011},
  address   = {Nancy, France},
  publisher = {Association for Computational Linguistics},
  pages     = {91--101},
  url       = {http://www.aclweb.org/anthology/W11-2812}
}