For UPSC Prelims preparation, selecting the right books is crucial. Here are some highly recommended books across various subjects:

General Studies Paper-I

1. Indian Polity
   • “Indian Polity” by M. Laxmikanth
   • “Introduction to the Constitution of India” by D.D. Basu
2. Indian History
   • “Spectrum’s A Brief History of Modern India” by Rajiv Ahir
   • “Ancient India” by R.S. Sharma
   • “Medieval India” by Satish Chandra
   • “India’s Struggle for Independence” by Bipan Chandra
3. Geography
   • “Physical Geography” by Savindra Singh
   • “Indian Geography” by Majid Husain
   • “Certificate Physical and Human Geography” by G.C. Leong
4. Environment and Ecology
   • “Environment and Ecology” by Majid Husain
   • “Shankar IAS Environment” by Shankar IAS Academy
5. Current Affairs
   • “The Hindu” or “The Indian Express”
   • Monthly current affairs magazines like “Yojana”, “Kurukshetra”, or “Economic and Political Weekly”
6. General Science
   • “NCERT Science Textbooks” (Class 6-10)
   • “General Science for Civil Services Preliminary Examination” by S.A. Majid

General Studies Paper-II (CSAT)

1. Aptitude and Reasoning
   • “CSAT Paper 2: General Studies Paper 2” by Arihant Publications
   • “Quantitative Aptitude for Competitive Examinations” by R.S. Aggarwal
   • “Verbal and Non-Verbal Reasoning” by R.S. Aggarwal
2. Comprehension and Logical Reasoning
   • “CSAT: Civil Services Aptitude Test Paper II” by M. Karthikeyan

Other Resources

1. Previous Years’ Papers
   • “UPSC Civil Services Preliminary Examination Solved Papers”
   • “UPSC Prelims Previous Years’ Papers”
2. Online Resources and Test Series
   • Consider enrolling in reputable online test series and using apps for practice.

These books should provide a comprehensive base for your preparation. Tailor your reading based on your strengths and weaknesses, and regularly review and revise the material to reinforce your learning.