What are the best books on social media marketing?

I’d like some recommendations for books about social media marketing. Specifically, best practices and examples of how companies are using sites like Facebook/Myspace/Twitter to build their businesses.

Thanks

What are the best books to read on social media?

I am interested in learning more about social media theories and best practices. I was wondering if anyone could recommend any good books. It has been tricky to find good information since the industry is changing so rapidly. Any recommendations? Thank you!
I am referring to social media online. Thank you!

Books On Social Media

Some Books we are currently reading , and will review in the future :

The New Community Rules , 1st Edition

by Tamar Weinberg.

5 Amazing Social Media Related Books You Need To Read

Sure, we all know there is a wealth of information to be had on the interwebs for free, but, and that’s a big but, you should always keep in mind the source of said information. A lot of it is accurate, a lot of it isn’t – that’s for you and the community to figure [...]