Why? : percobaan dan pengamatan

 Novianti, Endah Nawang; Jeon, Jae; Woon;

Jakarta : Elex Media Komputindo , 2013

Why? information technology = why? teknologi informasi

 Cho, Young; Seon; Supriyadi, Denny;

Jakarta : Elex Media Komputindo , 2010