Most of the books on the first list represent those I would only read once, and never again (or never at all, like "Head First [Anything]"). The C Programming L

Most of the books on the first list represent those I would only read once, and never again (or never at all, like "Head First [Anything]"). The C Programming Language and Refactoring are the exceptions. K&R was one of the textbooks in my first CS class, and the first CS book I read which was still useful to me 10 years later. The books on the second list which I have read (at least partially) are books I have had reason to go back to at some point in my career, and any of them which I no longer have, I will likely purchase again.