Variations on Intermediate Sudoku Logic Puzzles (Vol 1) 
 Chapter 34: Four Easy Sudoku-7D Puzzles (numbers 185-188) 
 
-  Step-by-step instructions for solving  Puzzle 185, (27/49)   Diff: 3/994
 -  Step-by-step instructions for solving  Puzzle 186, (30/49)   Diff: 4/9991
 -  Step-by-step instructions for solving  Puzzle 187, (30/49)   Diff: 4/9991
 -  Step-by-step instructions for solving  Puzzle 188, (31/49)   Diff: 4/9496