Chiaro, Delia
Routledge, 1992
Buku Teks
Diem Ihsan, author
Universitas Sriwijaya, 2011
Buku Teks
Cohen, David, author
Routledge, 2006
Buku Teks
edited by Charles E. Schaefer and Kevin J. O'Connor
John Wiley & Sons, 1982
Buku Referensi
Carmichael, Karla D., author
Pearson - Prentice Hall, 2006
Buku Teks