Variations on Intermediate Sudoku Logic Puzzles (Vol 1) 
 Chapter 30: Four Medium Sudoku-7C-2V Puzzles (numbers 161-164) 
 
-  Step-by-step instructions for solving  Puzzle 161, (35/49)   Diff: 5/9.9781
 -  Step-by-step instructions for solving  Puzzle 162, (39/49)   Diff: 6/87.6981
 -  Step-by-step instructions for solving  Puzzle 163, (41/49)   Diff: 8/6453.5593
 -  Step-by-step instructions for solving  Puzzle 164, (41/49)   Diff: 8/5434.4786