Longo’s Absolutely Nasty Level 4
KrazyDad SuperTough v5 #5
Paul Stephens from Weeks and Addicts
Shortz Ferocious Beware! Very Challenging
Shortz Trickiest Beware
KrazyDad Insane v4 #5 2019
Pitkow GM and Super GM
Pitkow’s Super GMs
Pitkow Expert
Nikoli’s Sudoku X-tremes
Wayne Gould’s Train Your Brain Su Doku Fiendish
Antoine Alary’s More Extreme
Gordon’s Mensa Guide
Weekly Extreme
Snyder’s Sadistic Sudoku
Longo’s Nastiest Sudoku Ever
Carol Vonderman Master Sudoku
A.D. Ardson’s Very Hard v.2
Rebecca Bean Extremely Hard
David Badger’s Hard Sudoku
Manuel Castillo’s Only Hard Sudoku
Castillo’s Only Extreme Sudoku Updated
Moito Very Hard Highest Rated
A. D. Ardson Sudoku Diabolical
Rebecca Bean Extremely Hard Sudoku v.10
World’s Hardest Sudoku Book
Funster Extremes
Will Shortz’s Hard Sudoku Beware I
James Forest’s [Very Hard] Classic Sudoku
Castillo’s Only Extreme Updated
Lucky Panda [Extremely Hard] Sudoku
PencilPress 500+ Extreme Sudoku
Sheldon Master Class Updated
F__ These Puzzles Are Hard
David Challenger’s Super Fiendish
J.B. Nakamoto Sudoku[Extreme Level]
Stefan Heine’s Ultrahardcore Right Pages I
Stefan Heine’s Ultrahardcore Right Pages II
