Columbia subject headings:
Africa--Colonization--History--20th century.
Irrigation projects--Sahara--History--20th century.
Mediterranean Sea--History--20th century.
Reclamation of land--Mediterranean Region--History--20th century.
Sörgel, Herman, 1885-1952.
Harvard subject headings:
Princeton subject headings:
Africa--Colonization--History--20th century.
Irrigation projects--Sahara--History--20th century.
Mediterranean Sea--History--20th century.
Reclamation of land--Mediterranean Region--History--20th century.
Sörgel, Herman, 1885-1952.