Kunarjo, author
UI-Press, 2003
Buku Referensi
Steinberg, Roberta, author
Prentice-Hall, 1987
Buku Teks
Trisakti International Center for Service studies FE-Usakti, 2006
Majalah, Jurnal, Buletin
Anggrahini Kusumowardhani, author
1986
UI - Skripsi (Membership)
Timpe, A. Dale, author
Elex Media Komputindo, 1993
Buku Teks