Bibliografi : hlm. 170-172
No Inv.: 9385-9389/P/Perp/92/5c
No Inv.: 118297-118299/P/Perp/09/3c
No Inv.: 865/S/Perp/98/1c~107079-107081/S/Perp/06/3c
No Inv.: 78742/01/1c
No Inv.: 111575-111577/P/Perp/07/3c
No Inv.: 877/S/Perp/92/1c~115072/S/Perp/08/1c
No Inv.: 297/S/Perp/91/1c
Judul asli :"The Essence of information systems"
No Inv.: 3471/P/Perp/98/1c