Atheism: A Very Short Introduction
Disbelief 101: A Young Person's Guide to Atheism
Atheism: The Case Against God (The Skeptic's Bookshelf)
Atheism: A Beginner's Handbook: All you wanted to know about atheism and why
Raising Freethinkers: A Practical Guide for Parenting Beyond Belief
Atheism Explained: From Folly to Philosophy (Ideas Explained)
Then Why Do I Have Toenails?: How To Be The Best Atheist You Can Be.
Atheist Universe: The Thinking Person's Answer to Christian Fundamentalism