| title | ISBN-13 | year of publica- tion | other author(s) |
|---|---|---|---|
| Lo spaccacervelli. Livello 1. Principiante | 978-88-6298-398-3 | 2015 | Carolyn Skitt · Robert Allen |
| Lo spaccacervelli. Livello 2. Intermedio | 978-88-6298-399-0 | 2015 | Carolyn Skitt · Robert Allen |
| Lo spaccacervelli. Livello 3. Esperto | 978-88-6298-400-3 | 2015 | Carolyn Skitt · Robert Allen |
| Mensa | 978-1-84732-100-8 | 2008 | Carolyn Skitt |
| Mensa: Boost Your IQ: 2 | 978-1-85868-311-9 | 1997 | " |
| Mensa Kids Brain Busters: Number Crunching Puzzles | 978-1-84732-487-0 | 2010 | " |
| Mensa Mighty Mind Benders Boost Your IQ | 978-0-09-178616-8 | 1994 | " |
| Mensa Mighty Mindbenders: Test Your Intelligence with These Mind-boggling Puzzles, Brain-teasers, and Mazes | 978-1-4351-1700-6 | 2009 | Robert Allen · Carolyn Skitt |
| Mensa Number Puzzles | 978-1-85868-309-6 | 1997 | |
| Train Your Brain: Brain-Bending Challenges: Intermediate | 978-1-4380-0538-6 | 2014 | Robert Allen · Carolyn Skitt |
| Train Your Brain: Brain-Scrambling Challenges | 978-1-4380-0766-3 | 2015 | Robert Allen · Carolyn Skitt |
| Train Your Brain Cranium Crunchers | 978-1-4380-0845-5 | 2016 | Robert Allen · Carolyn Skitt |
| Train Your Brain: Mind-Melting Conundrums | 978-1-4380-0767-0 | 2015 | Robert Allen · Carolyn Skitt |
| Train Your Brain: Mind-Twisting Puzzles: Beginner | 978-1-4380-0537-9 | 2014 | Robert Allen · Carolyn Skitt |
| Train Your Brain Perplexing Puzzles | 978-1-4380-0846-2 | 2016 | Robert Allen · Carolyn Skitt |
| Train Your Brain: Super Tricky Teasers: Expert | 978-1-4380-0539-3 | 2014 | Robert Allen · Carolyn Skitt |
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