Ruth Ann and Wald Amberstone run The Tarot School and have already published a really useful Tarot book called 'Tarot Tips'.
One of those Tarot Tips was on finding secret paths from one card to another card by means of the shared symbols on cards. Well, although not directly related to that particular Tip it is a fabulous aid to spotting the shared symbols because, the Secret Language of Tarot details all the shared symbols in the RWS deck.
Laid out as a series of lessons (as you might find with their Tarot School) it is a comprehensive guide to the symbolism in the RWS. I think that it's another extremely useful book from the Amberstones!
I gave the book 5 stars despite the fact that it only really suits RWS decks (it doesn't deal with the symbolism of any other type of deck). So, in that respect, it is limited in its application. But then the RWS *IS* the world's most popular deck and, heck, a book that tried to encompass ALL symbols in ALL decks would need to be wheeled about by a forklift truck!
Worth buying if you like using the RWS decks.