UPSC syllabus is vast and covers a wide range of topics. If you have time, it is advisable to start with the NCERT textbooks (Class 6 to 12) for subjects like History, Geography, Science, and Economics, as they provide a strong foundation for UPSC preparation. After you are done with NCERTs, move to standard books as mentioned below: History: Modern: India's Struggle for Independence by Bipan Chandra or History of Modern India by Spectrum Publications Ancient: India's Ancient Past by R.S. Sharma Medieval: Old NCERT by Satish Chandra Mastering World History by Norman Lowe Indian Polity: Indian Polity by M. Laxmikanth or Introduction to the Constitution of India by D.D. Basu Governance in India by Laxmikanth Geography: Class XI and XII NCERTs (2 books each) Certificate Physical and Human Geography by Goh Cheng Leong Oxford School Atlas by Oxford University Press Economy: Indian Economy by Ramesh Singh Economic Survey and Budget General Science: Current Affairs from newspapers and magazines Environment and Ecology: Shankar IAS Environment Ethics, Integrity, and Aptitude: Ethics, Integrity, and Aptitude by G. Subba Rao Current Affairs: The Hindu or The Indian Express newspaper (for daily news) Yojana magazine