Columbia subject headings:
Chad--Dependency on foreign countries.
Chad--Politics and government--1960-1990.
Chad--Relations.
Harvard subject headings:
Chad--Dependency on foreign countries.
Chad--Politics and government--1960-
Chad--Relations--Foreign countries.
Princeton subject headings:
Chad--Dependency on foreign countries.
Chad--Politics and government--1960-1990.
Chad--Relations--Foreign countries.