suggest me book

Institute Material is very good for its presentation or to score good marks. No need to try other books. However, you try to study all compilations and RTPs of SM. Its more than sufficient to score good marks.

Yeah i'll second Krishna's suggestion..

Better read from Institute material and then Practice manual of strategic management  (cost of Practice Manual is Rs. 75)

you can order latest Practice manual from  https://www.icai.org/publications.html

however if you are not comfortable with them just follow

Paduka then  Dinesh Madan 

good luck for studies

if you find material's language tough than go for Dinesh Madan