You can check below recommended books for your preparation

Engineering Mathematics

Discrete Mathematics and Its Applications by Kenneth Rosen

Higher Engineering mathematics by B.S. Grewal

Advanced Engineering Mathematics by Erwin Kreyszig

Digital Logic

Digital Design by Morris Mano

Digital Electronics by S. Salivahanan & S. Arivazhagan

Computer Organization and Architecture

Computer Architecture – A Quantitative Approach by Hennessy and Patterson

Computer Organization and Embedded systems by Carl Hamacher

Programming and Data Structures

The C Programming language by Dennis Richie

Classic Data Structures by Debasis Samanta

Algorithms

Introduction to Algorithms by Cormen
Data Structures & Algorithms by R.S. Salaria

Theory of Computation

An Introduction to Formal Languages and Automata by Peter Linz

NPTEL lectures by Kamala Krithivasan

Compiler Design

Compilers: Principles, Techniques and Tools by Aho & Ullman

Compiler Design in C by Allen I Holub

Operating System

Operating System Concepts by Galvin

Modern Operating System by Andrew Tanenbaum

Operating Systems by Stallings

Databases

Database System Concepts by Henry. F. Korth

Normalization and indexing by Shamkant B. Navathe

Computer Networks

Computer Networking: A Top-Down Approach

Data Communications and Networking by Kurose & Ross and Behrouz A. Forouzan

Computer Networks by Peterson & Davie