Hi Nandhini, thanks for your response, can you please check aboove two links for me. And tell me which link I should follow. https://upscbuddy.com/upsc-books/ https://www.clearias.com/ias-books/ 

Hello Rahul,Yes , I did go through both the sites! and I feel that clearias is good. But for your kind reference, please do not buy all those books and you need not.For example, take geography-they have mentioned all the available books. But I recommend you G.C.Leong's and Oxford atlas alone. You can supplement the others with current affairs and mock tests.Second Environment- It is enough if you go through Shankar Ias book alone. Need not go for all the three.Then coming to polity, Indian Polity (5th edition prefered) by M.Laxmikanth is alone enough. You may suppement it with The Indian constitution but you need not study the entire book.Hope you understood. Thank you!