Books recommended on r/logic

The most-mentioned books on r/logic.

A Mathematical Introduction to Logic
4 users
Metalogic
4 users
A Beginner's Guide to Mathematical Logic
3 users
First-Order Logic
3 users
Beginning Logic
3 users
Language, Proof and Logic
3 users

Looking for more? Similar subreddits are cryptography, MachineLearning, matheducation, minimalism, and simpleliving.