I think someone here mentioned having the presskit many pages back.
Old magazines with THX articles circa '71 do pop up on Ebay. Cinefantastique being the one I see most often. Could have sworn there was an AC issue up several months ago as well.
Does anyone have this magazine?
The movie was Amercian Zoetrope's flagship production, so there was likely more mainstream coverage than if it was some weird little Italian Sci Fi flick.
THX also got a bit of retrospective coverage in the many Starlog clones that saw print in the wake of Star Wars.