BertoniMT79'

@article{DBLP:journals/ipl/BertoniMT79,
  author    = {Alberto Bertoni and
               Giancarlo Mauri and
               Mauro Torelli},
  title     = {Three Efficient Algorithms for Counting Problems},
  journal   = {Inf. Process. Lett.},
  volume    = {8},
  number    = {1},
  year      = {1979},
  pages     = {50-53},
  ee        = {http://dx.doi.org/10.1016/0020-0190(79)90093-0},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}