Yes, and they use burner phones, too. So the writer may be known, but not the name of the person Page leaked to. The leakee would have given the info to the writer. I think we need to rethink our espionage laws to criminalize the journalists who receive and publicize state secrets. Their first amendment rights do not, IMO, include the right to conspire to harm the interests of the nation.
I believe that SCOTUS ruled differently in the Pentagon Papers case [New York Times Co. v. United States]. Perhaps there is room for interpretation - I am not a legal beagle.