Absolutely Nasty Sudoku: Even Nastier – Level 4

Peter Gordon is the Editorial Director of Puzzlewright Press. He was a member of the winning US teams at the 1990 International Crossword Marathon in Bjelovar, Yugoslavia, and the 1999 World Puzzle Championship in Budapest, Hungary. In 1994, he represented the US at the Rummikub world championship on a cruise up the Rhine River, and he is the two-time division winner at the American Crossword Puzzle Tournament. His titles include Hall of Fame Crosswords, Yahtzee Scratch & Play, Match Wits With Mensa: Test Your Trivia Smarts, and Verbiage for the Verbose; he is also the co-author of Solitaire Battleships and Scrabble-doku.

Frank Longo has written over 90 sudoku books, including Oy Vey! Sudoku; 10×10 Sudoku; Mensa® Absolutely Nasty Sudoku Level 1, 2, 3, and 4; The Worlds Longest Sudoku Puzzle; and The Sudoku Code (co-authored with Francis Heaney).