Difficult Sudoku Twelve Logic Puzzles (Vol 1) 
 Chapter 11: Six Difficult (DiffLev 9-11) tpsmith-silly Puzzles (numbers 85-90) 
 
-  Step-by-step instructions for solving  Puzzle 85, (87/144)   Diff: 9/9.9889.9892
 -  Step-by-step instructions for solving  Puzzle 86, (90/144)   Diff: 10/97.5889.9993
 -  Step-by-step instructions for solving  Puzzle 87, (88/144)   Diff: 11/999.9922.1458
 -  Step-by-step instructions for solving  Puzzle 88, (93/144)   Diff: 11/989.8598.9941
 -  Step-by-step instructions for solving  Puzzle 89, (96/144)   Diff: 11/987.8999.9982
 -  Step-by-step instructions for solving  Puzzle 90, (96/144)   Diff: 11/742.7799.9991