Peter G. Hinman 
Fundamentals of Mathematical Logic [PDF ebook] 

This introductory graduate text covers modern mathematical logic from propositional, first-order and infinitary logic and Gödel”s Incompleteness Theorems to extensive introductions to set theory, model theory and recursion (computability) theory. Based on the author”s more than 35 years of teaching experience, the book develops students” intuition by presenting complex ideas in the simplest context for which they make sense. The book is appropriate for use as a classroom text, for self-study, and as a reference on the state of modern logic.