Bennahum, David S.
Basic Books , 1998
Buku Teks
Oxford University Press , 1990
Buku Teks
Wertheim, Margaret
Doubleday , 1999
Buku Teks
Spinello, Richard A., author
Jones and Bartlett Learning, 2017
Buku Teks
Dodge, Martin
Addison Wisley, 2001
Buku Referensi