Number Theory & Recreational Math
- Magic Squares, Magic Stars & Other Patterns (Harvey Heinz)
- Prime Curios (G. L. Honaker, Jr.)
- The Prime Pages (Chris Caldwell)
- Prime Puzzles and Problems Connection (Carlos Rivera)
- World!Of Numbers (Patrick De Geest)
- Number Recreations (Shyam Sunder Gupta).
- Definitions of Numbers (Tanya Khovanova)
School Math Sites