Variations on Intermediate Sudoku Logic Puzzles (Vol 1) 
 Chapter 39: Four Easy Sudoku-8 Puzzles (numbers 217-220) 
 
-  Step-by-step instructions for solving  Puzzle 217, (33/64)   Diff: 4/9973
 -  Step-by-step instructions for solving  Puzzle 218, (37/64)   Diff: 4/9992
 -  Step-by-step instructions for solving  Puzzle 219, (37/64)   Diff: 4/9991
 -  Step-by-step instructions for solving  Puzzle 220, (38/64)   Diff: 4/9993