books by subject
Mathematical Theory
The Times Su Doku Book 4: 100 original puzzles: Bk. 4
The Times Su Doku Book 2: 100 original puzzles
How Mathematicians Think: Using Ambiguity, Contradiction, and Paradox to Create Mathematics
The Times Killer Su Doku 2: 100 challenging puzzles from The Times (The Times Su Doku)
