Challenging Sudoku Twelve Logic Puzzles (Vol 1) 
 Chapter 3: Twelve Challenging (DiffLev 15-17) Sudoku-12 Puzzles (numbers 1-12) 
 
-  Step-by-step instructions for solving  Puzzle 1, (82/144)   Diff: 15/984.7646.5432.6571
 -  Step-by-step instructions for solving  Puzzle 2, (87/144)   Diff: 15/997.3431.1234.9993
 -  Step-by-step instructions for solving  Puzzle 3, (84/144)   Diff: 16/9333.6533.4635.4998
 -  Step-by-step instructions for solving  Puzzle 4, (86/144)   Diff: 16/9523.1224.9979.9542
 -  Step-by-step instructions for solving  Puzzle 5, (90/144)   Diff: 16/9555.3334.5797.7444
 -  Step-by-step instructions for solving  Puzzle 6, (83/144)   Diff: 17/5.54C4.4579.643B.6841
 -  Step-by-step instructions for solving  Puzzle 7, (86/144)   Diff: 17/9.6622.3332.32C4.9996
 -  Step-by-step instructions for solving  Puzzle 8, (87/144)   Diff: 17/9.7795.2343.5544.3433
 -  Step-by-step instructions for solving  Puzzle 9, (88/144)   Diff: 17/6.8542.2346.9798.5242
 -  Step-by-step instructions for solving  Puzzle 10, (91/144)   Diff: 17/9.8753.1273.3112.6999
 -  Step-by-step instructions for solving  Puzzle 11, (92/144)   Diff: 17/8.3212.B334.5734.7997
 -  Step-by-step instructions for solving  Puzzle 12, (95/144)   Diff: 17/6.3476.5993.3655.6683