Biagi, Shirley, author
Wadsworth and Cengage Learning, 2012
Buku Teks
Biagi, Shirley, author
Cengage Learning, 2015
Buku Teks
Sheehan, Michael, author
Prentice-Hall, 1991
Buku Referensi
Unesco Press, 1976
Buku Teks
O`Shea, Robert P., author
Harcourt Brace , 1996
Buku Teks