@inproceedings{conf/focs/Gottlob93,
  title = "NP Trees and Carnap's Modal Logic",
  author = "Georg Gottlob",
  year = "1993",
  booktitle = "34th Annual Symposium on Foundations of Computer Science, 3-5 November 1993, Palo Alto, California, USA",
  pages = "42-51",
  publisher = "{IEEE}",
}