The Pictorial Key to the Tarot
The Pictorial Key to the Tarot is A. E. Waite's guide to divinatory tarot, published in conjunction with the Rider-Waite-Smith deck. Waite was very concerned with the accuracy of the symbols he used for his deck, and he did much research into the traditions, interpretations, and history behind the cards.
Two different versions of the book were published. The first, published in 1909, was called The Key to the Tarot. The second, published in 1910, added illustrations of the tarot cards by Pamela Colman Smith and was called The Pictorial Key to the Tarot.