hello aspirant.

IAS Books For English Language Comprehension – Prelims Paper 2 (CSAT)

• UPSC PORTAL: English Language Comprehension Skills (CSAT Series Book)
• English Comprehension / Reading Comprehension.
• 30 Days To A More Powerful Vocabulary by Wilfred Funk.
• English Reading Comprehension by Anjani A Gupta.
• Essential English for Competitive Examinations - 2nd Edition  by  Dr. Rashmi singh.
• List of English Literature books for IAS exam:
  • Introduction to English Literature by W. H Hudson
  • The Routledge History of Literature in English
  • A short History of English Literature (Pramod K. Nayar)
  • King Lear- William Shakespeare
  • The Tempest- William Shakespeare
  • Hard Times- Charles Dickens
  • The Adventures of Huckleberry Finn- Mark Twain
  • Kanthapura-Raja Rao
  • A House for Mr. Biswas- V.S. Naipal

(https://www.amazon.in/s/ref=dp_byline_sr_book_1?ie=UTF8&field-author=Dr.+Rashmi+Singh&search-alias=stripbooks) List of Important IAS Books for hindi Exam

• 7 Varsh Upsc IAS/ Ips Mains Hindi (Anivarya) Year-Wise Solved Papers (2013 - 2019)
  
• Aadhunik Sahitya ki Pravritiyan – Namavar Sinha
• Jaayasee Aakalan ke Aayaam- Sadanand Shaahee
• Kabeer –Param Anand Srivastav
• Kabeer ke Sabad – Dr. Sukadev Sinha
• Khadi Boli ka Prarambhik Swaroop – Nilesh Jain
• Mahaabhoj Mulyankan ke Paripekshy – Sadaanand Shaahee
• Mohan Raakesh aur Ashadh ka Ek din –Gireesh Rastogi
• Niraala Rachita Raam Kee Shakti Pooja Bhaashy –Dr. Surya Prasaad Dikshit
• Prasda Aura Skandgupta – Dr. Rvatramana
• Triveni – Acharya Ramachandra Shukla

Hope this helps you

Hello aspirant,

There is a compulsory Indian Language paper and English paper in the mains examination.

Study Material for Hindi Language Paper (Hindi compulsory paper UPSC book):

• Samanya Hindi Book by Unique Publications
• UPSC question papers of the past 10 years

The minimum marks required for the compulsory INdian language paper is 30 percent i.e. 90 out of 300 marks.

For English Paper you should read following books-

• Compulsory English by A.P. Bhardwaj
• Contemporary Essays For Civil Services Examinations by Ramesh Singh

Hope it helps.

Thanks.