edited by Kathleen E. Hug
Office of International Infrmation Programs US Department of State, [Date of publication not identified]
Buku Teks SO
Gultom, Samuel
Greenwood Press, 1987
Buku Referensi
Office of International Information Programs, 1991
Buku Teks SO
Birdsall, Stephen S.
John Wiley & Sons, 1992
Buku Teks SO
United State Information Agency, 1994
Buku Teks SO