What one programming book have you actually read twice?

Question

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What is the single most influential book every programmer should read?

I've aquired and discarded so many programming books it's embarrasing. But a few I've re-read and kept nearby as a reference and to share with others. These books I think of fondly as I would a favorite novel.

Many of us can recite a list of classic programming books. Some deserve mention here, but I'm hoping to discover other lesser known volumes. So, of all the tomes that have found a home on your bookshelf, what one programming book have you actually read twice, and why?

Answer 1

The Michael Abarash black book (and articles.)

Answer 2

Code Complete: I've rolled through it front to back more than twice, and I get more out of it every time.

Answer 3

Structure and Interpretation of Computer Programs, because I didn't really "get it" the first time :)

Answer 4

Numerical recipes in C++ vol 3. I read it more than twice, and I read the older version more than twice too.