I can't find a purchased iBook, what could have happened to it?

So, I purchased an iBook a while back, I wanted to download it onto my iPad, but it's not showing up in my purchased. The book is called Five Nights at Freddy's: The Silver Eyes. When I first bought it, I saw two of them that looked exactly the same, same cover, same author, same everything. But now I can only see one version on the iBook store. The book is still on my phone because I bought it from there. I've tried doing it from my iMac, but it's not even showing up there either. It's almost like it disappered. Is there a way I can some how get it onto my iPad without having to buy it again?