Variations on Intermediate Sudoku Logic Puzzles (Vol 1) 
 Chapter 21: Eight Difficult Sudoku-7B-X Puzzles (numbers 105-112) 
 
-  Step-by-step instructions for solving  Puzzle 105, (37/49)   Diff: 9/6.3544.4551
 -  Step-by-step instructions for solving  Puzzle 106, (39/49)   Diff: 9/2.3446.4754
 -  Step-by-step instructions for solving  Puzzle 107, (39/49)   Diff: 10/31.1B38.9453
 -  Step-by-step instructions for solving  Puzzle 108, (41/49)   Diff: 10/22.4434.2686
 -  Step-by-step instructions for solving  Puzzle 109, (38/49)   Diff: 12/4321.2333.4454
 -  Step-by-step instructions for solving  Puzzle 110, (40/49)   Diff: 12/2211.3248.8522
 -  Step-by-step instructions for solving  Puzzle 111, (40/49)   Diff: 12/1131.A1A2.6796
 -  Step-by-step instructions for solving  Puzzle 112, (41/49)   Diff: 12/3212.3432.2478