Can you suggest the reference book for mathematics? I have no idea about the statistics.

Hello Phani, Here are some books of Mathematics which can help you in CSIR NET exam preparation. Real Analysis - H. L. Royden Linear Algebra - Hoffman and Kunze Complex Analysis - R. V. Churchill Algebra - Joseph A. Gallian Topology - G. F. Simmons Ordinary & Partial Differential Equations MD

You can prefer NCERT mathematics as reference book to make your basics strong.