Hii!
To start preparing for UPSC entrance exam, you can refer to the following books-
* Indian Art and culture- Nitin Singhania
* Indian polity for civil service examination- M. Lakshmikant
* Oxford school Atlas- Oxford publication
* Indian economy- Ramesh Singh
* A brief history of modern India - Rajiv Ahir
* Indian year books
* Lucent's general knowledge book
* Panorama year book
* Newspapers ( daily ) ...very important
* NCERTs of all subjects available
* Previous year question papers
Hope this helps.
Good luck!

Hello Aspirant,

I am enlisting down some books which would be very helpful to you for your IAS preparation :-

@History

• India's Struggle for Independence by Bipin Chandra
• NCERT Textbook of Class 11th and 12th

@Geography

• Certificate Physical Geography by GC Leong
• NCERT Textbook of Class 11th and 12th
• World Atlas

@Indian Polity

• India Polity by M. Lakshmikanth
• NCERT textbook of Class 11th and 12th

@Economy

• Indian Economy by Ramesh Singh
• Economic Development Policies in India by Jain and Hari
• NCERT textbook of Class 11th

@International Relations

• NCERT textbook of Class 12th
• Current affairs

@CSAT

• Tata McGraw Hill CSAT Manual
• CSAT II by Arihant Publication
• Verbal and Non-verbal reasoning by RS Agarwal

I hope this information helps you.

Good Luck!!