Challenging Sudoku Twelve Logic Puzzles (Vol 1) 
 Chapter 6: Twelve Challenging (DiffLev 19-20) Sudoku-12up Puzzles (numbers 37-48) 
 
-  Step-by-step instructions for solving  Puzzle 37, (87/144)   Diff: 19/844.4441.1BA1.2456.9974
 -  Step-by-step instructions for solving  Puzzle 38, (87/144)   Diff: 19/653.3232.4434.5579.8734
 -  Step-by-step instructions for solving  Puzzle 39, (90/144)   Diff: 19/952.213C.2246.6667.7693
 -  Step-by-step instructions for solving  Puzzle 40, (92/144)   Diff: 19/811.3752.5872.4535.9922
 -  Step-by-step instructions for solving  Puzzle 41, (84/144)   Diff: 20/9634.3113.3434.5567.6442
 -  Step-by-step instructions for solving  Puzzle 42, (86/144)   Diff: 20/9944.621C.35A1.2476.6561
 -  Step-by-step instructions for solving  Puzzle 43, (88/144)   Diff: 20/9456.4224.3693.3431.2554
 -  Step-by-step instructions for solving  Puzzle 44, (92/144)   Diff: 20/7512.5454.5997.3323.6533
 -  Step-by-step instructions for solving  Puzzle 45, (93/144)   Diff: 20/7321.1233.6553.5953.8993
 -  Step-by-step instructions for solving  Puzzle 46, (94/144)   Diff: 20/9634.8523.4311.C235.9993
 -  Step-by-step instructions for solving  Puzzle 47, (95/144)   Diff: 20/7142.1343.3657.5448.9972
 -  Step-by-step instructions for solving  Puzzle 48, (95/144)   Diff: 20/644D.3361.2456.9756.4571