1. Ann L. Winblad, Samuel d. Edwaards, David R. King-“Object-Oriented Software”: Addison-Wesley, 1990.
2. M. Armstrong, Richard J. Mitchell, “Uses and Abuses of Inheritance” Journal Enginnering Software, Vol 9 (1) 19–26, Jan 1994
3. M. Barbut, B. Monjardet, «Ordre et classification», Algèbre et combinatoire, Tome II, 1970, Hachette.
4. H. Belaid, Ali Jaoua, “Abstraction of Objects by Conceptual Clustering”, In proceeding of Joint Conference on Information Sciences, Durham, USA, 1997.
5. N. Belkhiter, C. Bourhfir, M.M. Gammoudi, A. Jaoua, N. Le Thanh, M. Reguig, «Architecture rectangulaire optimale d’une base documentaire indexée», Université Laval, Département d’Informatique (Rapport de Recherche), DIUL-RR-9201, 1992.