Hi Kath
You could copy the URL of your Book resource on the front page and then add a URL resource (paste the URL into the link area) to the course you want to put it in. If you want it in all site courses, you may want to try adding an HTML 'sticky block' and paste/link the URL of the Book into whatever wording is appropriate.
Here is an example of linking to another page within text.....Click >Here< to read more about a 'sticky block'.