@inproceedings{gatt-portet-2011-may,
    title = "If it may have happened before, it happened, but not necessarily before",
    author = "Gatt, Albert  and
      Portet, Fran{\c{c}}ois",
    editor = "Gardent, Claire  and
      Striegnitz, Kristina",
    booktitle = "Proceedings of the 13th {E}uropean Workshop on Natural Language Generation",
    month = sep,
    year = "2011",
    address = "Nancy, France",
    publisher = "Association for Computational Linguistics",
    url = "https://aclanthology.org/W11-2812/",
    pages = "91--101"
}