Challenging Sudoku-by5 Logic Puzzles (Vol 1) 
 Chapter 6: Sixteen Challenging (DiffLev 18) Sudoku-by5 Puzzles (numbers 49-64) 
 
-  Step-by-step instructions for solving  Puzzle 49, (238/369)   Diff: 18/99.9999.971D.3135.4688
 -  Step-by-step instructions for solving  Puzzle 50, (242/369)   Diff: 18/99.9999.9999.7534.6444
 -  Step-by-step instructions for solving  Puzzle 51, (244/369)   Diff: 18/99.9999.9999.8985.4785
 -  Step-by-step instructions for solving  Puzzle 52, (248/369)   Diff: 18/99.9999.9982.B474.8633
 -  Step-by-step instructions for solving  Puzzle 53, (250/369)   Diff: 18/99.9999.9999.9998.5892
 -  Step-by-step instructions for solving  Puzzle 54, (250/369)   Diff: 18/99.9999.9999.9779.9934
 -  Step-by-step instructions for solving  Puzzle 55, (250/369)   Diff: 18/99.9999.9995.5999.9451
 -  Step-by-step instructions for solving  Puzzle 56, (255/369)   Diff: 18/99.9999.9999.9999.9994
 -  Step-by-step instructions for solving  Puzzle 57, (258/369)   Diff: 18/99.9736.9999.9999.9992
 -  Step-by-step instructions for solving  Puzzle 58, (262/369)   Diff: 18/99.9997.9999.9999.9996
 -  Step-by-step instructions for solving  Puzzle 59, (263/369)   Diff: 18/99.9999.9999.9987.9993
 -  Step-by-step instructions for solving  Puzzle 60, (263/369)   Diff: 18/99.9999.9999.7689.7842
 -  Step-by-step instructions for solving  Puzzle 61, (266/369)   Diff: 18/99.9999.9999.9999.9855
 -  Step-by-step instructions for solving  Puzzle 62, (266/369)   Diff: 18/99.9999.7999.9999.9992
 -  Step-by-step instructions for solving  Puzzle 63, (269/369)   Diff: 18/99.9964.9998.9999.9992
 -  Step-by-step instructions for solving  Puzzle 64, (273/369)   Diff: 18/99.9999.9997.9799.9999