| title | ISBN-13 | year of publication |
|---|---|---|
| Junior Sudoku X | 978-0-7553-1528-4 | 2006 |
| Sudoku X: Bk. 1: The Only Puzzle with the X Factor: Bk. 1 | 978-0-7553-1501-7 | 2005 |
| Sudoku X Book 1: The Only Puzzles With the X Factor | 978-1-932112-45-0 | 2005 |
| Sudoku X-mas | 978-0-7553-1502-4 | 2005 |
| Sudoku Xpert | 978-0-7553-1529-1 | 2006 |
| Sudoku Xtreme | 978-0-7553-1530-7 | 2006 |
| The Laker story | 978-0-9508007-0-7 | 1982 |
| Tottering-by-Gently Out and About with the Totterings | 978-0-7112-3084-2 | 2010 |
Christensen in association with Sunday telegraph · Frances Lincoln · Headline · Justin, Charles & Co.