@article{372965,
      author = {Hughes, G. E. and Cresswell, M. J.},
      url = {http://library.usi.edu/record/372965},
      title = {A new introduction to modal logic [electronic resource] /},
      publisher = {Routledge,},
      recid = {372965},
      pages = {x, 421 p. :},
      address = {London ;},
      year = {1996},
}