@article{DBLP:journals/ipl/GronauM07,
  author    = {Ilan Gronau and
               Shlomo Moran},
  title     = {Optimal implementations of UPGMA and other common clustering
               algorithms},
  journal   = {Inf. Process. Lett.},
  volume    = {104},
  number    = {6},
  year      = {2007},
  pages     = {205-210},
  ee        = {http://dx.doi.org/10.1016/j.ipl.2007.07.002},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}