A couple of thoughts come to mind.
First, in all of those CIA denials… "no journalist is employed by this Agency" or something similar. Doesn't say they're not contractors or working through third parties. Very carefully chosen wording that leaves the door open for all sort of third-party arrangements.
#2. This Congressional document that is on intelligence.senate.gov. It seems that it came from the Boston library (see PDF page 48). Why on earth would Congress need to get one of it's own documents from the Boston public library?