I did it successfully! I just now:
1. In iTunes, I chose the "Books" category from the little drop-down menu at left,
2. Used File -> Add to Library ...
3. Imported my iBook into iTunes
4. When I started to drag the iBook icon towards the right, a panel displayed at right that contained an icon representing my iPad ... I dropped the iBook icon onto the iPad
5. The iBook opened within the "iBooks" app on my iPad