Columbia subject headings:
Libraries--Handbooks, manuals, etc.
Religion--Research--Handbooks, manuals, etc.
Theology--Reference books.
Harvard subject headings:
Libraries--Handbooks, manuals, etc.
Religion--Research--Handbooks, manuals, etc.
Theology--Reference books.
Princeton subject headings:
Libraries--Handbooks, manuals, etc.
Reference books--Theology.
Religion--Research--Handbooks, manuals, etc.