Ebook For SSC CGL

Where I will download Ebooks for Math Reasoning and English? I have only a book of General Knowledge of India. Now I want all these books in PDF format. So provide name of some websites where I will download ebooks of Math Reasoning and English subjects of SSC CGL Exam? Can I get question papers from that websites?

Tell me the link of the website fro where I will get the E-Book of the Staff Selection Commission Combined Graduate Level Examination SSC CGL exam? Suggest me the best authors of the books for the SSC CGL exam?