As you have asked about the recommended books for the IAS preliminary exam, I am giving you osme infomraiton about it, I am mentioning them

Essential IAS Books For UPSC Prelims

History Of Modern India – Bipan Chandra. (History)
India’s Struggle For Independence – Bipan Chandra. (History)
India’s Ancient Past – R.S. Sharma. (History)
History Of Medieval India – Satish Chandra. (History)
The Wonder That Was India – A.L. Bhasham. (Culture)
Indian Art and Culture – Nitin Singhania. (Culture)
Geography of India – Majid Husain. (Geography)
Oxford School Atlas – Oxford. (Geography)
Certificate Physical and Human Geography – Goh Cheng Leong. (Geography)
Indian Polity for Civil Services Examinations – M. Laxmikanth. (Polity)
Indian Economy – Ramesh Singh. (Economy)
Economic Survey. (Economy)
Science and Technology in India – TMH. (Science and Technology)
Environmental Studies: From Crisis to Cure – Rajagopalan. (Environment)
Environment for Civil Services Prelims and Mains – Khuller. (Environment)
India Year Book (Current Affairs)
Manorama Yearbook. (Current Affairs)
CSAT Paper – 2 Manual by TMH or CSAT-II – Arihant (CSAT – Paper 2)
Analytical Reasoning – M. K. Pandey (CSAT – Paper 2: Analytical Reasoning)
Verbal & Non-Verbal Reasoning – R. S.Aggarwal (CSAT Paper 2: Reasoning