Wilson, George P., author
F.S. Crofts, 1947
Buku Teks
Cutts, Martin, author
Oxford University Press, 1995
Buku Teks
Shurter, Robert L.
McGraw-Hill, 1959
Buku Teks
Burt, Angela, author
Stanley Thornes, 1995
Buku Referensi
Flesch, Rudolf
Harper & Brothers, 1958
Buku Teks