which books should be referred for preparing cat as I can't go to an centre for preparing

The best book for Verbal ability is Arun sharma Mcgraw hill education, For Quants DI and Logical Reasoning again Arunsharma is best author. For Quants you can also refer to Nishit Sinha for Preparation of complex problems. For verbal Ability, Book by Word power made easy is must recommended. If you're finding difficult with above books you can take up TIME coaching material notes as well with solution sets.

Also, do join at least 1 mock test series. It will help you practice in a test-like environment.

Get material the coaching institutes like TIME, Career Launcher, PT education etc if you can't go and get coaching there as they do keep a structured format of each and every exam with mocks.
For Quant you can refer Arun Sharma and Sarvesh Verma. Just buy one of the above. That will be more than enough if you complete the whole book.
For data interpretation  and logical reasoning you can refer coaching institute material from Handa ka Funda IMS / TIME / Career Launcher as your first resource. This material is very well designed and keeps the needs of students as the first priority. If you still need books then you can go for Arun Sharma's 1. How to prepare for Data Interpretation for the CAT
2. How to prepare for Logical Reasoning for the CAT or you can also refer books by pearson, Nishit K. Sinha for all topics.
For verbal you can refer 'word power and easy' by Norman Lewis and 'How to prepare for verbal ability and reading comprehension' by Arun Sharma & Meenakshi Upadhaya.

You can go through this link for topics you need to prepare for CAT.

Read newspaper everyday for verbal ability as it will help in reading comprehension, vocabulary and your reading speed will be enhanced. Also read few more books during the preparation for vocabulary and general awareness (fiction, biographies etc)

And keep taking mock tests and analyse result after every test you take.

All the best!