LiuT73'

@article{DBLP:journals/cacm/LiuT73,
  author    = {C. N. Liu and
               D. T. Tang},
  title     = {Enumerating Combinations of m Out of n Objects [G6] (Algorithm
               452)},
  journal   = {Commun. ACM},
  volume    = {16},
  number    = {8},
  year      = {1973},
  pages     = {485},
  ee        = {http://doi.acm.org/10.1145/355609.362322},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}