Columbia subject headings:
Apologetics--Early works to 1800.
Apologetics--History--Middle Ages, 600-1500.
God--Early works to 1800.
Theology--Early works to 1800.
Harvard subject headings:
Apologetics--Early works to 1800
God--Early works to 1800
Islam--Controversial literature
Theology--Early works to 1800
Princeton subject headings: