Hi Aakash,

Reference books are not necessarily needed when you have this much of study material. It's totally up to your call.

If you want to brush your preparation more I'll suggest you go for online practise papers.

There are online mock test packages you can purchase one of your choice, this will give you an idea about the paper pattern and type of questions.Further you can also refer and subscribe to youtube channels they are really helpful.

some online portals also provide platform for queries and doubts regarding questions.