Bolton, William, 1933-
Longman Scientific & Technical, 1992
Buku Teks
Loveday, George
Longman, 1995
Buku Teks
Robinson, Vester
Reston Publishing Company, 1974
Buku Referensi
Mourad, Samiha
John Wiley & Sons, 2000
Buku Teks
Lenk, John D.
McGraw-Hill, 1993
Buku Referensi