Variations on Intermediate Sudoku Logic Puzzles (Vol 1) 
 Chapter 9: Four Easy Sudoku-7B Puzzles (numbers 37-40) 
 
-  Step-by-step instructions for solving  Puzzle 37, (23/49)   Diff: 4/9751
 -  Step-by-step instructions for solving  Puzzle 38, (30/49)   Diff: 4/9961
 -  Step-by-step instructions for solving  Puzzle 39, (30/49)   Diff: 4/9952
 -  Step-by-step instructions for solving  Puzzle 40, (31/49)   Diff: 4/9983