Columbia subject headings:
Apologetics--History--20th century.
Catholic Church--Doctrines--History.
Catholic Church--Relations.
Christianity and other religions.
Religious pluralism--Christianity.
Theology, Doctrinal--History.
Harvard subject headings:
Apologetics--History--20th century
Christianity and other religions
Christianity and other religions.
Religious pluralism--Christianity
Theology, Doctrinal--History.
Princeton subject headings: