The Theory of the Riemann Zeta-Function 2nd Edition by E.C. Titchmarsh (Author) - This is  a P.D.F Ebook.

'This is a book from which you will be able to learn how to do mathematics', and we cannot do better than repeat this advice with all the confidence that comes from knowing that it has been endorsed by those best situated to discover that it was sound, namely, the students who have followed it.