Hi Pranjal,NCERT books are most important for the basic concept building. Also, you can refer HC Verma and I E Irodov for Physics; ML Khanna, SL Loney, Hall & Knight for Mathematics; P.Bahadur for Physical Chemistry ,OP Tondon and J.D Lee for Inorganic Chemistry and Morrison & Boyd for Organic Chemistry.Also, there are many JEE toppers in Spanedea faculty.If you are enrolled into a course with one of those faculties you will get their notes as reference material.