Very nice to have an open access version. The paper version is really expensive if your salary isn't in dollars. I've regretted to by the print Brazilian editio

Very nice to have an open access version. The paper version is really expensive if your salary isn't in dollars. I've regretted to by the print Brazilian edition. O'Reilly is my favorite technical publisher, but the non English editions are crap. My book didn't have an index, making it useless as a reference.