About iTunes 10.5.3:
iTunes 10.5.3 allows you to sync interactive iBooks textbooks to your iPad. These Multi-Touch textbooks are available for purchase from the iTunes Store on your Mac or from the iBookstore included with iBooks 2 on your iPad.
iBooks textbooks are created with iBooks Author — now available as a free download on the Mac App Store.
For information on the security content of this update, please visit: support.apple.com/kb/HT1222
Download: iTunes 10.5.3 x86 | 64-bit (Windows) | macOS