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Let’s say you are reading Alice’s Adventures in Wonderland, and you’d like your friends to read it with you (or you have a witty comment to let loose). Simply click on the Google+ Share box on the About the Book page or in a Google Books preview, enter your message, then select which circles you’d like to share details about the book with, and click ‘share’.
Sharing a book on Google+ will show its cover, the description and title, and links back to the About the Book page on Google Books. More info can be found at 