Columbia subject headings:
Catholic Church--Doctrines--History--20th century.
Christian ethics--Catholic authors.
Christian ethics--United States--History--20th century.
Harvard subject headings:
Catholic Church--Doctrines--History--20th century.
Christian ethics--Catholic authors
Christian ethics--United States--History--20th century.
Princeton subject headings:
Catholic Church--Doctrines--History--20th century.
Christian ethics--Catholic authors.
Christian ethics--United States--History--20th century.