1. Bastiani(-Ehresmann), A., Ehresmann, C.: Categories of sketched structures. Cahiers Top. et Géom. Dif. XIII-2 (1972). Reprinted in Ehresmann, A.C. (ed.): Charles Ehresmann, Œuvres complètes et commentées, Partie IV-1, Amiens (1983)
2. Duval, D., Lair, C.: Diagrammatic specifications. Rapport de Recherche IMAG-LMC 1043 (2002)
3. Edelman, G.M., Gally, J.A.: Degeneracy and complexity in biological systems. Proc. Natl. Acad. Sci. USA 98, 13763–13768 (2001)
4. Ehresmann, A.C., Vanbremeersch, J.-P.: Hierarchical Evolutive Systems: A mathematical model for complex systems. Bull. of Math. Bio. 49(1), 13–50 (1987)
5. Ehresmann, A.C., Vanbremeersch, J.-P.: Memory Evolutive Systems: An Application to an aging theory. In: Cybernetics and Systems, pp. 190–192. Tata McGraw Hill Pub., New Delhi (1993)