Columbia subject headings:
Apologetics--History--20th century.
Knox, Ronald Arbuthnott, 1888-1957.
Lewis, C. S. (Clive Staples), 1898-1963--Religion.
Harvard subject headings:
Apologetics--History--20th century
Knox, Ronald Arbuthnott, 1888-1957.
Lewis, C. S. (Clive Staples), 1898-1963
Princeton subject headings: