Variations on Advanced Sudoku Logic Puzzles (Vol 1) 
 Chapter 40: Four Medium HyperSudoku-15 Puzzles (numbers 131-134) 
 
-  Step-by-step instructions for solving  Puzzle 131, (93/225)   Diff: 5/9.9994
 -  Step-by-step instructions for solving  Puzzle 132, (120/225)   Diff: 7/999.9932
 -  Step-by-step instructions for solving  Puzzle 133, (120/225)   Diff: 7/999.9864
 -  Step-by-step instructions for solving  Puzzle 134, (113/225)   Diff: 8/9999.2442