edited by Edward J. Blakely
Human Science Press, 1979
Buku Teks
edited by P.W.D. Matthews and G.W. Ford
Sun Books, 1968
Buku Teks
Department of Economic Affairs, 1953
Buku Teks
Balassa, Bela A., author
Harvester Wheatsheaf, 1989
Buku Teks
United Nations
United Nations, 1977
Buku Teks