Currently, I’m also preparing for my IAS exam after going through Dhyeya IAS and it’s going very well for me. In these days, I found some important books that will help you in IAS prelims:
History:
– India’s Struggle for Independence – Bipan Chandra
– Facets of Indian Culture – Spectrum
Geography:
– Certificate Physical Geography – G C Leong
– World Atlas
Indian Polity:
– Indian Polity – M Laxmikanth
– NCERT IX-XII
Economics:
– Indian Economy by Ramesh Singh
– Economic Development & Policies in India – Jain & Ohri
International Relations:
– NCERT XII (Contemporary World Politics)
– Current Affairs
CSAT:
– Tata McGraw Hill CSAT Manual
– Verbal & Non-Verbal Reasoning – R S Aggarwal