These commemorative collections of essays in honor of senior scholars and are often the best or only place to find a complete bibliography of an art historian's writings. Many classic essays (e.g. Panofsky's "Imago Pietatis") first appeared in Festschriften, and many of these essays have never been reprinted. (In the pre-LC Fine Arts stacks (those cataloged prior to 2010), they are classed at N 5302...)
Rave, P.O. Kunstgeschichte in Festschriften. (1962)
Avery Reference N35 R19
Coverage to 1960.
Rounds, D., ed. Articles on Antiquity in Festschriften. (1962)
Butler Reference R016.93 R76