For the UPSC (Union Public Service Commission) exam, a comprehensive and dedicated reading list is essential. The preparation typically involves covering subjects from NCERT books (National Council of Educational Research and Training) to standard reference books, along with staying updated on current affairs. Here's a general overview of the important books you would need to read:

NCERT Books (Classes VI to XII): These form the foundational base for your UPSC preparation. Focus on History, Geography, Polity, Economics, and Science. They provide a clear and simple understanding of the basic concepts.

For Indian History:

• Ancient India: R.S. Sharma
• Medieval India: Satish Chandra
• Modern India: Bipan Chandra (India's Struggle for Independence) and Spectrum (A Brief History of Modern India)

For Indian Polity:

• Indian Polity by M. Laxmikanth
• Introduction to the Constitution of India by D.D. Basu (selective reading)
• NCERT books on Political Science

For Indian Economy:

• Indian Economy by Ramesh Singh or Nitin Singhania
• Economic Survey (latest)
• NCERT books on Economics

For Geography:

• Certificate Physical and Human Geography by Goh Cheng Leong
• NCERT books on Geography (Classes VI to XII)
• Oxford School Atlas

For Environment and Ecology:

• Environmental Studies by R. Rajagopalan
• Relevant chapters from NCERT Biology books
• Current environmental issues

For Art and Culture:

• Indian Art and Culture by Nitin Singhania
• NCERT book on Indian Heritage and Culture (Class XI)

For Science and Technology:

• NCERT books on Science (Classes VI to X)
• Current developments in science and technology

For Ethics, Integrity, and Aptitude (GS Paper IV):

• Ethics, Integrity and Aptitude by G. Subba Rao and P.N. Roy Chowdhury
• Lexicon for Ethics, Integrity & Aptitude by Niraj Kumar
  (https://superkalam.com/blog/how-to-write-answers-in-upsc-mains-daily-practice) (https://superkalam.com/blog/how-to-write-answers-in-upsc-mains-daily-practice)

For Current Affairs:

• The Hindu or The Indian Express newspaper
• Yojana and Kurukshetra magazines
• Press Information Bureau (PIB) releases
• Regularly follow online news portals and current affairs websites.

For Optional Subject: The books for your chosen optional subject will depend entirely on the subject itself. You will need to research and select standard books and study material relevant to your chosen optional.