Needless to say, none of this is necessary to get started. If you are interested, however, I have a list here of books, that have helped me understand more about the human condition in general and Yoga in specific and might also help you.
I believe, that viewing things from many perspectives can greatly add to our understanding, therefore I do not solely recommend “Yoga Books”. When I began, Yoga to me was the “new perspective”, as opposed to western Philosophy and I have always admired the wisdom inherent in the worlds mythologies and our great literature. The western medical approach to Yoga poses is currently what I try to understand better.
Please note: I do not get paid in any way to provide certain links or to promote certain books.