Columbia subject headings:
Database searching--United States--Handbooks, manuals, etc.
Government information--United States--Databases--Handbooks, manuals, etc.
United States--Information services--Databases--Handbooks, manuals, etc.
Harvard subject headings:
Database searching--United States--Handbooks, manuals, etc.
Government information--United States--Databases--Handbooks, manuals, etc.
United States--Information services--Databases--Handbooks, manuals, etc.
Princeton subject headings: