hi,

I have mentioned some books name below which you may find helpful,

Objective English by S.P Bakshi

Word Power made easy by Norman Lewis

quantitive aptitude by rs agarwal,

Analytical Reasoning by MK Pandey

Modern Approach to Verbal Reasoning by R.S. Aggarwal

General Knowledge by Lucent

bankars adda magazine for current affairs

for chsl you need to really have good grip on english and gk, as time is less but questions is more. if you get 80% questions correctly attempt from english and gk then it is a plus point. I suggest you to regularly practice numerical aptitude to make yourself faster in solving questions.

all the best for exams.