Columbia subject headings:
Harvard subject headings:
Engineering--Africa, Portuguese-speaking--History.
Portugal--History--Colonies--Africa.
Railroads--Africa, Portuguese-speaking--History.
Princeton subject headings:
Portugal--Colonies--Africa--History--19th century.
Portugal--Colonies--Africa--History--20th century.
Railroads--Angola--History--19th century.
Railroads--Angola--History--20th century.
Railroads--Mozambique--History--19th century.
Railroads--Mozambique--History--20th century.