Surreal Numbers
On Numbers and Games
The Symmetries of Things
How to Solve It: A New Aspect of Mathematical Method (Princeton Science Library)
On Quaternions and Octonions
Genius At Play: The Curious Mind of John Horton Conway
Infinite Powers: How Calculus Reveals the Secrets of the Universe
My Best Mathematical and Logic Puzzles (Dover Recreational Math)
Regular Polytopes
Introduction to Graph Theory (Dover Books on Mathematics)