Ted Smart, 2001. 1st Thus. Paperback. Allen, Ivan. 64 pages. 'Solve the Sums, Seek the Crystal!' Solutions at end of book. Pages beginning to tan. Very Good.
Harcourt, 2003. Hardback. Stringer, Lauren. Pictorial laminated boards. Dustwrapper repeats cover design. 27cm x 29cm. Some small tears to dustwrapper edge. Very Good.