DS read one or two of those resource books probably around the same age. I don't remember the exact names because they are not part of our personal library. We borrowed them from the public library. One of them was a DK book, with lots of pictures of different currencies as well as a good amount of text on the country/history. Not sure if it was from the DK book, but I seem to recall something about the history of currencies as well because DS wanted to discuss it with me.