Hein, Eleanor C., author
Lippincott , 2001
Buku Teks
Artikel Jurnal
edited by Rodolfo C. Severino and Lorraine Carlos Salazar
ISEAS, 2007
Buku Teks
Tariq, Hussain, author
Random House, 2006
Buku Teks
Schuler, Randall S., author
West Publishing, 1996
Buku Teks