Columbia subject headings:
Economics--United States--Information services.
Libraries and electronic publishing--United States.
Library surveys--United States.
Harvard subject headings:
Economics--Databases.
Information storage and retrieval systems--Economics
Libraries and electronic publishing--United States.
Library surveys--United States.
Princeton subject headings:
Databases.
Economics--Databases.
Information storage and retrieval systems--Economics.
Libraries and electronic publishing--United States.
Library surveys--United States.