You can add hyperlinks to both text and image. A link can take the reader to an external web address or a page within the book.
NOTE: Hyperlinks are not enabled in Book Creator until you export the book to iBooks (or another ebook reader). The links will not work if you try to tap on them whilst editing the book.
Adding hyperlinks to text:
1. Long tap on a word
In the Add Text screen perform a long tap to display a menu with the Link option.
2. Choose 'Link'
Tap on Link and in the displayed window you can provide the link itself, and also the optional title text displayed for the link.
To link to a specific page in your book just enter the number e.g. 5. You can also use any type of valid link (see the end of this article for examples).
Please note: adding hyperlinks to text requires iOS 6.0 or later.
Hyperlinks for images
You can add a link to an image using the Inspector. With your image selected tap on i and then enter the hyperlink details.
Please note: Be careful where you place the image if you want it to hyperlink. The edges of pages are reserved for page turning in iBooks, so may override your image link if it's too close to the edge of the page.
Alongside page numbers and standard http:// links you can also do the following:
An email address
A telephone number
Example: tel:+44-20-8123-4567 (hyphens are optional)
In iBooks on an iPhone a telephone link will call the number. On an iPad or iPod Touch the reader can add the number to their contacts.
Tip: Provide the international code when creating the link – your reader might be in a different country!
A link into another app
Some apps support custom links. If you can be sure a specific app is installed this can be a great way to enhance your book. Here’s an example that would open the Twitter app and draft a tweet:
There is a good listing of apps with custom links at handleopenurl.com
From the blog:
>> Using non-linear stories to gamify your books (great use of hyperlinks)