What are some recommended proof books for strengthening math abilities?

[Physteo]

Hi guys! I writing to you because I need an help. I need to strenghten my abilities to make proofs in maths. I would like to have some suggestions, something usefull to read, ...
Thank you :)

 

[Mark44]

There are several books out there. Here are a couple of titles:
The Nuts and Bolts of Proofs, Antonella Cupillari, Wadsworth Publishing Co.
Math Proofs Demystified, Stan Gibilisco, McGraw-Hill