“Solution to double partition Alphametics”, Knuth Donald, The Art of Computer Programming, Pre-Fascicle 2b, Generating All Permutations, Addison-Wesley, 12 June 2004, p. 42. http://www-cs-faculty.stanford.edu/~knuth/taocp.html#vol4
“Solution to double partition Alphametics”, Knuth Donald, The Art of Computer Programming, Pre-Fascicle 2b, Generating All Permutations, Addison-Wesley, 12 June 2004, p. 42. http://www-cs-faculty.stanford.edu/~knuth/taocp.html#vol4