Staley, Eugene
Published for the Council on Foreign Relations by Harper, 1961
Buku Teks
George Allen and Unwin, 1963
Buku Teks
Benham, Frederic
Oxford University Press, 1962
Buku Teks
Fituni, L.A.
Progress Publishers, 1963
Buku Teks
Belshaw, Horace
Food and Agriculture Organization of the United Nations, 1959
Buku Teks