University Paperbacks
Another odd series, in that it was evidently simultaneously published in England by Methuen, and some listings mention Barnes & Noble in reference to later Methuen publications. It's kind of a mess. I'm limiting this only to titles I can establish were published in the US under the Barnes & Noble University Paperbacks line (up to UP 72 around 1966-1967).
Barnes & Noble Sets Up Scholarly Paperback Series, PW, Mar. 21, 1960, at 30-31 (announcing the University Paperbacks series for publication starting April 1960).
Ad, PW, Oct. 3, 1960, at 19-22 (showcasing the launch of both the American Authors and Critics Series and the University Paperbacks).