He's moved on to bigger and better things, but authority (http://nathanbarry.com/authority/ http://nathanbarry.com/authority/) is supposedly the definative guid

He's moved on to bigger and better things, but authority (http://nathanbarry.com/authority/ http://nathanbarry.com/authority/) is supposedly the definative guide to this topic. I haven't read it yet because he removed the eBook only option (this, as I understand it, is part of the trick to making money self publishing: present everything as a premium package instead of a boring old book).