Variations on Sudoku-by5 Logic Puzzles (Vol 1) 
 Chapter 21: Three Tournament Education-Xtreme Puzzles (numbers 55-57) 
 
-  Step-by-step instructions for solving  Puzzle 55, (267/369)   Diff: 27/994.7999.9999.9994.C245.5589.9951
 -  Step-by-step instructions for solving  Puzzle 56, (260/369)   Diff: 28/9946.9999.9999.8979.9444.2234.9994
 -  Step-by-step instructions for solving  Puzzle 57, (276/369)   Diff: 29/9.9953.7646.6799.9999.9834.7979.9999