By Alan Cash
By Ian Stewart (, Professor of Mathematics, University of Warwick)
By Various Experts
By Meredith MacArdle
By Frank Longo
By Steve Tribe, Steve Tribe
By Nick Fawcett
By Steve Curtis
By Elaine Higgleton, Catherine Schwarz
By David McGaughey, Jack Waley-Cohen, Richardson Puzzles and Games
By Prion
By Roy Preston, Sue Preston
By Scholastic
By Bill O'Neill
By G. T. Karber
By Mark Mason
By Compiled By Barbour Staff