@inproceedings{staudacher-1993-new, title = "New Frontiers Beyond Context-Freeness: Di-Grammars and Di-Automata.", author = "Staudacher, Peter", editor = "Krauwer, Steven and Moortgat, Michael and des Tombe, Louis", booktitle = "Sixth Conference of the {E}uropean Chapter of the Association for Computational Linguistics", month = apr, year = "1993", address = "Utrecht, The Netherlands", publisher = "Association for Computational Linguistics", url = "https://preview.aclanthology.org/fix-sig-urls/E93-1042/" }