Elliott, Inger McCabe
Clarkson N. Potter Inc, 1984
Buku Referensi
Hutton, Peter
APA Publications, 1993
Buku Referensi
December, John
Prenhalindo, 1997
Buku Teks SO
Ariswara
Intermedia, 1992
Buku Teks SO
Harold, Elliotte Rusty
IDG Books Worldwide, 1997
Buku Teks SO