Hello divya

Since I am from the same field as yours so I did like to have a small discussion over it . Since you want to be a topper you can join any coaching institute as they will provide you better guidance and more importantly better study materials .Or you can just buy some good study materials and read them by yourself to safe the time of spending classes . Take arihant (or another publications ) previous years solved papers .Which will give you a good idea . I personally don't want to recommend books as I think you must follow the syllabus and books usually have a lot more than necessary . But obviously if you can then you can chose books .But since you are in msc I don't think you have enough time now .