Wolf, Charles
Syracuse University Press, 1958
Buku Teks
Prentice-Hall, 1949
Buku Teks
Fituni, L.A.
Progress Publishers, 1963
Buku Teks
Nurkse, Ragnar, 1907-1959
Oxford University Press, 1961
Buku Teks
Belshaw, Horace
Food and Agriculture Organization of the United Nations, 1959
Buku Teks