Georges Grosz Colette Rolland Sylviane R. Schwer Carine Souveyet Véronique Plihon Samira Si-Said Camille Ben Achour Christophe Gnaho Modelling and Engineering the Requirements Engineering Process: An Overview of the NATURE Approach. 115-131 1997 2 Requir. Eng. 3 db/journals/re/re2.html#GroszRSSPSAG97 http://dx.doi.org/10.1007/BF02802771