Hello Supriya

Here i am listing down few important books which can help you in your preparation:

Code of Civil Procedure

Bare Act, Takwani

Transfer of Property Act

Bare Act, Poonam Pradhan (lexis Nexis)

Indian Contract Act

Bare Act, Avtar Singh

Other than these books you can follow UPSC IQ Magazine or it's official You tube channel which is Study IQ.