Variations on Advanced Sudoku Logic Puzzles (Vol 1) 
 Chapter 39: Four Easy HyperSudoku-15 Puzzles (numbers 127-130) 
 
-  Step-by-step instructions for solving  Puzzle 127, (91/225)   Diff: 4/9992
 -  Step-by-step instructions for solving  Puzzle 128, (94/225)   Diff: 4/9992
 -  Step-by-step instructions for solving  Puzzle 129, (103/225)   Diff: 4/9991
 -  Step-by-step instructions for solving  Puzzle 130, (106/225)   Diff: 4/9991