Source: https://www.researchgate.net/profile/Natacha-Trehan/publication/269525161_La_fonction_Achats_de_demain_analyse_prospective_par_la_methode_PM/links/5a579429aca2726376b66571/La-fonction-Achats-de-demain-analyse-prospective-par-la-methode-PM.pdf