Books library location

My Mac mini's internal hard drive is pretty small, and yet I have a large library of audiobooks in the Books app. Apparently all those audiobooks are stored in the Library folder of my user account, and that means they need to be on the same hard drive that I boot from.

Ideally, I'd like to move my Books library to a larger external drive. I know you can do this with your Music and Photos libraries, but I can't find any way to do this with Books.

Is there any way to get my Books library onto an external drive?

Thanks!