How to transfer an epub on my old iphone to my new iphone?

So on my old phone which is an iphone 4, I had an ibook downloaded from epubbud.com downloaded, and i want to transfer it onto my new iphone 5s, but i don't know how because its not syncing to cloud and its obviously not in my purchases. I have a pc by the way.

Hi, iPhone Transfer software allows you to transfer various files like music/movie/Pictures/TV Shows/Podcast/iTunes U/eBooks/Camera Roll/Ringtone/SMS/Contacts/Voice memos/Camera shot between any two iOS devices.

Epub file is ebook file. You can use a 3rd party software like this MobileTrans to transfer the ebook. You just need to connect your iPhone 4 and iPhone 5s to computer with the cables, then you can drag and drop the epub file between them.