I rely on technical books on certain subjects. For instance, I would get a technical book on compiler design patterns because those are pretty timeless. On the

I rely on technical books on certain subjects. For instance, I would get a technical book on compiler design patterns because those are pretty timeless. On the other hand, I have stopped buying books that are new programming language specific because the languages tend to change and make the book obsolete. I've experienced this with a RoR/Ruby book I bought that wouldn't even work with the newest version of RoR at the time. The book was useless.