My dad loves the romans and is pretty well read on them, however I’d like to find some information to share with him.

It’s his birthday soon and for that I’ve bought him a coin from Caracalla’s reign. He is his favourite emperor. The coin is a silver denarius with an elephant on. Where can I find more information about this coin or coins from this reign? It seems like it’s be a fairly specialist bit of info.

I’m after either books about it that I can get for him, or, some more information that I can type up into a nice feature for him.

PS. If this is the wrong place to ask, then where should I go?

Pics if they help: https://i.imgur.com/w9gE6Pu.jpg https://i.imgur.com/TIU2Htq.jpg