@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}
}