Freeing a Book from the Book App!

A couple of years ago, I bought two books from a medical journal and downloaded them onto the home screen of my laptop. I see the books on the home screen, but when I click on them, I am taken to the Apple Book app. I cannot access the books because an old Apple ID shows up. I haven't used that ID for three years. Another problem is that the books are listed in the Apple Bookstore for $4.99 each. I already paid the journal for them several years ago. The books might have ended up in the Book App when data was transferred from my earlier iMac Pro to this new Mac Air I now have. Is there anything I can do to open the books and not have to buy them again?