Columbia subject headings:
Delp, Alfred.
History--Philosophy--History--20th century.
History--Religious aspects--Christianity--History of doctrines--20th century.
Harvard subject headings:
Delp, Alfred.
History--Philosophy--History--20th century
History--Religious aspects--Christianity--History of doctrines--20th century
Princeton subject headings:
Delp, Alfred.
History--Philosophy.
History--Religious aspects--Christianity.
Thieme, Karl.