The Point of Adoption (PoA) is not to be confused with the critical mass ‘inflection point’ on the S-curve [67,68]; or with the ‘tipping pint’, the critical threshold introduced by Gladwell .
 M. Gladwell, The Tipping Point: How Little Things Can Make a Big Difference, Abacus,
 E.M. Rogers, Diffusion of Innovations, Free Press, New York, 1995.
 E.M. Rogers, U.E. Medina, M.A. Rivera, C.J.Wiley, Complex adaptive systems and the
diffusion of innovations, Innov. J. Public Sect. Innov. J. 10 (3) (2005) 1–26.