compiled by Jonathan French Scott and Alexander Baltzly
F.S. Crofts & Co., 1930
Buku Teks
Meller, Helen, author
John Wiley & Sons, 2001
Buku Teks
Stearns, Peter N., author
Macmillan, 1967
Buku Teks
Williams, E.N., author
Allen Lane, 1980
Buku Referensi
Welch, David, author
Heinemann, 1994
Buku Teks