Herget, James E.
Texas: Rice University Press, 1990,
Buku Referensi
Herget, James E.
Rice University Press, 1990
Buku Referensi
Cowan, Thomas A.
Oceana Publications, Inc, 1967
Buku Teks
Curzon, L.B.
CavendishPublishing Limited, 1992
Buku Teks
Wacks, Raymond
Blackstone Press limited, 1999
Buku Teks