Columbia subject headings:
Harvard subject headings:
Egypt--Foreign economic relations--Libya--Congresses.
Egypt--Foreign economic relations--Sudan--Congresses.
Libya--Foreign economic relations--Egypt--Congresses.
Libya--Foreign economic relations--Sudan--Congresses.
Sudan--Foreign economic relations--Egypt--Congresses.
Sudan--Foreign economic relations--Libya--Congresses.
Princeton subject headings:
Egypt--Foreign economic relations--Libya--Congresses.
Egypt--Foreign economic relations--Sudan--Congresses.
Libya--Foreign economic relations--Egypt--Congresses.
Libya--Foreign economic relations--Sudan--Congresses.
Sudan--Foreign economic relations--Egypt--Congresses.
Sudan--Foreign economic relations--Libya--Congresses.