TY  - BOOK
AU  - Velleman,Daniel J.
TI  - How to prove it: a structured approach 
SN  - 0521675995
AV  - QA9  .V44 2006
PY  - 2006///
CY  - New York
PB  - Cambridge University Press
KW  - Logic, Symbolic and mathematical
KW  - Mathematics
ER  -