Columbia subject headings:
Christianity and other religions.
Origen. Contra Celsum.
Paganism.
Harvard subject headings:
Apologetics--History--Early church, ca. 30-600
Celsus (Platonic philosopher), active 180.
Christianity and other religions--Greek
Origen. Contra Celsum.
Theology--History--Early church, ca. 30-600
Princeton subject headings:
Christianity and other religions.
Origen. Contra Celsum.
Paganism.