I was looking for this book but it appear that is out of print and the only copies available are very expansive, so what book would you recommend on GR? I mean, i want some in-depth textbook.
Although this is no replacement for a book, I would also recommend watching the following video assuming you know calculus and are familiar with Special Relativity. It goes so well until 1:38:53 and then it is bit rushed. Great intro nonetheless.