By Jack Waley-Cohen, Sinclair McKay, Joe Kerr, The Difficult Second Quiz Book 978-1785944598, 1785944592, 9781785944598, The Official Quiz Book 978-1785943683, 1785943685, 9781785943683, Bletchley Park Brainteasers 978-1472252609, 1472252608, 978147225260...
By GCHQ, Sinclair McKay, Joe Kerr, The GCHQ Puzzle Book II 978-0241365434, 0241365430, 9780241365434, Bletchley Park Brainteasers 978-1472252609, 1472252608, 9781472252609, The Scotland Yard Puzzle Book 978-1472258335, 1472258339, 9781472258335, The Bumpe...
