Introduction to Algorithms (3rd ed.). MIT Press and McGraw-Hill. pp. 191–193. ISBN 0-262-03384-4. ↑ Mark Wells, Applications of a language for computing in combinatorics, Information Processing 65 (Proceedings of the 1965 IFIP Congress), 497–498, 1966. ↑ Mark Wells, Elements of Combinatorial Computing, Pergamon Press, Oxford, 1971. ↑ Takumi Kasai, Shusaku Sawato, Shigeki Iwata, Thirty four comparisons are required to sort 13 items, LNCS 792, 260-269, 1994. ↑ Marcin Peczarski, Sorting 13 elements requires 34 comparisons, LNCS 2461, 785–794, 2002.