From abstract:

"The effect of social transmission on real-world voting was greater than the direct effect of the messages themselves, and nearly all the transmission occurred between ‘close friends’ who were more likely to have a face-to-face relationship. "

So people that already were most likely aligned ideologically.

So I assume that no reference makes even less an argument?

Well considering that you made the original claim, the burden of proof is on you. A simple Google search will also show you are wrong.

The article isn't accessible so I cannot examine the methodology. Have you read it in full?