The wonderfully, or perhaps horribly informative Encyclopedia that has served the world for so many years. Surely you know what this is about.
Gardner, Martin. "The Unexpected Hanging and Other Mathematical Diversions". Chicago: The University of Chicago Press, 1969.
Gardner, Martin. "Mathematical Magic Show". New York: Penguin Books, 1985.
Gardner, Martin. "Time Travel and Other Mathematical Bewilderments". New York: W. H. Freeman and Company, 1988.
The above three books by Martin Gardner were written about randomly selected mathematically recreational topics in layman's terminology. These topics include:
Lei Iat Seng. "http://www.cs.ust.hk/~philipl/index.html" Arion Lei Homepage. As of 25th June, 1998.
The homepage speaks for itself. Written by a "CoSysOp of the Paradise BBS (Fido 6:701/22) in Macau.", Who is "studying MPhil in Computer Science in HKUST".
Van Delft, Peter, and Jack Botermans. "Creative Puzzles of the World". Berkeley: Key Curriculum Press, 1995.
Many puzzles are delved into deeply in this informative and somewhat entertaining book.
Wells, David. "The Penguin Book of Curious and Interesting Numbers". London: Penguin Books Ltd., 1997.
A dictionary of numbers, exploring the most profound properties of certain numbers. It goes into extremely diverse fields of mathematics, such as geometry and (you guessed it) combinatorics.