Variations on Intermediate Sudoku Logic Puzzles (Vol 1) 
 Chapter 23: Four Easiest Sudoku-7C Puzzles (numbers 121-124) 
 
-  Step-by-step instructions for solving  Puzzle 121, (17/49)   Diff: 2/94
 -  Step-by-step instructions for solving  Puzzle 122, (17/49)   Diff: 2/91
 -  Step-by-step instructions for solving  Puzzle 123, (19/49)   Diff: 2/93
 -  Step-by-step instructions for solving  Puzzle 124, (20/49)   Diff: 2/92