Frank Longo creates, fact-checks, and edits crossword puzzles, and also specializes in sudoku, having published more than 150 sudoku books. His books have sold more than 5 million copies. His wide array of titles encompasses both standard and variety sudoku puzzles, and includesSip & Solve Simple Sudoku,The Peaceful Mind Book of Sudoku,Blockbuster Book of Sudoku,Beyond Black Belt Sudoku,and Puzzlewright Guide to Solving Sudoku (with Peter Gordon).