@article{372961,
      author = {Howson, Colin.},
      url = {http://library.usi.edu/record/372961},
      title = {Logic with trees an introduction to symbolic logic /  [electronic resource] :},
      publisher = {Routledge,},
      recid = {372961},
      pages = {xiii, 197 p. :},
      address = {London ;},
      year = {1997},
}