As per your request, I am recommended you some reference books for the Indian Engineering Services exam.

Optical Fiber Communication Optical Fiber Communication
Power Electronics Power Electronics
Power System Power System Engg.
CL Wadhwa
Electrical Machine Electrical Machinery
Nagrath & Kothari
Measurement and Instrumentation Electrical & Electronic Measurement and Instrumentation
H.S.Kalsi
Electrical Engineering Material Electrical Engineering Material
Network Theory Networks & Systems
Hayt
Microwave Engg. Microwave Devices & Circuits
Sanjeev Gupta
Pozar
Computer Engg. Microprocessor Architecture, Programming & Application
Stalling
Digital Electronics Digital Design
Tocci & Widmer
R.P.Jain
Electro Magnetic Theory Elements of Engg. Electromagnetics
Sadiku
W.H.Hayt
K.D.Prasad
Control System Control System Engg.
B.C.Kuo
B.S.Manke
Monochrome & Colour Monochrome & Colour
Satellite Communications Satellite Communications
Signal & System Signal & System
Communication System Communication System
Simon Haykins
Singh and Sapre
B.P.Lathi
Kennedyand Davis
Electronic Devices and Circuits & Analog Electronics-- Integrated Electronics: Analog & Digital Circuit & System
Sedra & Smith
J.B.Gupta
Ramakant A. Gayakwad
Streetman & Banerjee
S.M.Sze