Gaya APA

Beyer, H., Holtzblatt, K. (1998). Contextual Design : Defining customer- centerd system . USA: USA : Morgan Kaufmann Publisher, 1998.

Gaya MLA

Beyer, Hugh., Holtzblatt, Karen. "Contextual Design : Defining customer- centerd system". USA: USA : Morgan Kaufmann Publisher, 1998, 1998. Text.