Several years ago (2016) I purchased a number of ebooks (not from Apple). One sedandawk.epub I referred to occasionally, and wanted to lookup something.
It was missing from My Books on my iPad running iOS 13.1.2 (where I am certain I had read it before - at least on the predecessor of my new iPad which was initialised with a backup of the older iPad mini). The books are still on my iPad mini (original edition).
The book is in Books on my iMac (Retina 4K, 21.5-inch, 2017) running Catalina, and I can read it there. (MyBooks on the iPad only shows a small subset of those on my Mac.)
My question is HOW do I transfer to iPad. Previously I had probably used Dropbox, but now use Airdrop to transfer files, but this does not seem to be an option.
Secondary question - WHY did my books disappear from the iPad?