1. L.B. Arfa, A. Mili, L. Sekhri, Software maintenance management in Tunisia: a statistical study, in: Proceedings of ICSM 1990, IEEE, 1990, pp. 124–129.
2. L. Bergersen, Prosjektadministrasjon i systemutvikling: Aktiviteter i planleggingsfasen som påvirker suksess. PhD thesis, ORAL, NTH, Trondheim, Norway, 1990 (in Norwegian).
3. Software economics: status and prospect;Boehm;Information and Software Technology,1999
4. No silver bullet. Essence and accidents of software engineering;Brooks;IEEE Computer,1987
5. N. Chapin, Software maintenance types – a fresh view, in: Proceedings of the International Conference on Software Maintenance (ICSM’2000), 2000, pp. 247–252.