My friend introduces me to buy Rubank Advanced Method to practise finging. Any exercise book you all would recommand? Thanks

I really like Taffanel and Gaubert exercises. A lot of them are really difficult, but once you get used to them, they just "go". It`s weird-it`s like playing through some of those lines really loosens up my fingers, so if I don`t play my T&G before I start doing anything else, I feel like I can`t play.

Thanks!