@article{DBLP:journals/ipl/BertoniMP94,
  author    = {Alberto Bertoni and
               Carlo Mereghetti and
               Giovanni Pighizzini},
  title     = {An Optimal Lower Bound for Nonregular Languages},
  journal   = {Inf. Process. Lett.},
  volume    = {50},
  number    = {6},
  year      = {1994},
  pages     = {289-292},
  ee        = {http://dx.doi.org/10.1016/0020-0190(94)00056-5},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}