Challenging Sudoku Twelve Logic Puzzles (Vol 1) 
 Chapter 42: Two Challenging (DiffLev 19) Productively Puzzles (numbers 163-164) 
 
-  Step-by-step instructions for solving  Puzzle 163, (88/144)   Diff: 19/963.4523.2332.3364.9762
 -  Step-by-step instructions for solving  Puzzle 164, (88/144)   Diff: 19/844.44C1.2634.1242.5993