An Introduction to Gödel’s Theorems

Incompleteness and Computability: An Open Introduction to Gödel's Theorems (Open Logic Project Textbooks)

Gödel's Theorem: A Very Short Introduction

Introduction to Incompleteness: From Gödel's Theorems to Forcing and the Continuum Hypothesis

Introduction to Incompleteness: From Gödel's Theorems to Forcing and the Continuum Hypothesis