You can prefer below given books for GATE Mechanical Engineering:

Design of Machine Elements: By V.B. Bhandari

Engineering Mechanics: By Bhavikatti

Fluid Mechanics: by R K Bansal

Heat Transfer: by J P Hollman and R C Sachdeva

Industrial Engineering: by O P Khanna, Buffa and Sarin

Manufacturing Engineering:  by R.K. Jain

Strength of Materials: Gere & Timoshenko

Thermal Science: by P.K. Nag

Thermo Dynamics: Engineering Thermodynamics by P K Nag and Rajput

Theory of Machines: Theory of machines by Ratan

For further information more about you can go through with given below link.

GATE Mechanical Engineering Books

Good Luck!