Alphadoku image example, 25X25 sudoku puzzle, asymmetric, expert No. 10000.
9781523438945: 25 x 25 Suduko Puzzles: 75 Easy, Medium and Hard Sudoku Puzzles - Fry, Charlie: 1523438940 - AbeBooks
Giant Sudoku Puzzles: With solutions: 25X25 Puzzle Grid: Combined Alphabet letters A to P and Numbers 1 to 9 (Large Print / Paperback) | Klindt's Booksellers and Stationers