Brown, John Mason
Harper & Row, 1965
Buku Teks
McCullough, Helen Craig
Princeton University Press, 1980
Buku Teks SO
Times Books, 1991
Buku Referensi
Kay, Dennis
Twayne, 1995
Buku Teks
Bolton, Geoffrey Curgenven
Melbourne University Press, 1958
Buku Teks