There is no such thing. Paganisms are not "religions of The Book™." If we're talking historical and indigenous Paganisms, these all arose in pre-literate cultures, and were predominantly oral traditions, so not only are there no books, the written accounts we do have are typically from outsiders who weren't exactly impartial and objective chroniclers. It is also very important to remember that the notion of a religion being laid out in some singular book in a dogmatic fashion is an idea that comes from Abrahamic religions and is totally foreign to if not directly opposed to the essence of Paganisms. Contemporary Pagans, who aim to revive and recreate historical Pagan traditions, aren't about to introduce something that is so counter to its essence. Contemporary Paganism is a disorganized jumble of many, many traditions and anybody who attempted to come up with some unified doctrine would not be taken seriously. It has been said, and rightly so, that contemporary Pagans are people of the books (as in plural). The movement arose in the information age, and most of us learned about it by doing research, and develop our traditions by doing research. The notion of limiting oneself to a single book is honestly quite horrifying to me!