Harper, Robert Gale
John Wiley , 1978
Buku Teks
Smith, Alfred G.
Holt, Rinehart and Winston, 1966
Buku Teks
Damle, Y.B.
Mass Center for International Studies M.I.T. , 1955
Buku Teks
Haney, William V.
Ill Irwin , 1967
Buku Teks
edited by Sheldon S.L. Chang
John Wiley & Sons, 1983
Buku Referensi