Po45 Polya, G. How to Solve It. Princeton University Press, 1945.
MBS85 Mason, J.; Burton, L.; Stacey, K. Thinking Mathematically, rev. ed. Addison-Wesley, 1985.
Sc85 Schoenfeld, A. H. Mathematical Problem Solving. Academic Press, 1985.
De97 Devlin, K. Mathematics: The Science of Patterns. Scientific American Library, 1997.
Cu01 Cupillari, A. The Nuts and Bolts of Proofs, 2nd ed. Academic Press, 2001.
So02 Solow, D. How to Read and Do Proofs, 3rd ed. John Wiley and Sons, 2002.