Mayhead, Robin
Cambridge University Press, 1974
Koleksi Publik
Harrison, G.B.
Penguin Books, 1954
Buku Teks
Sampson, George
University Press, 1949
Buku Referensi
Wilson, John B.
Longmans Green , 1958
Buku Teks
Lewis, Roy
Penguin Books, 1949
Buku Teks