IIRC, "The Shallows: What the Internet Is Doing to Our Brains" had sources at the back. My copy is packed away and it's been awhile since I read it, so I could be wrong, but that's another that you might consider.

"Bowling Alone: The Collapse and Revival of American Community" is about a different topic - disconnection from community and social interactions that we used to have, but it's an overlapping topic. It has lots of data and graphs.