Robust estimation of the exponent function in the Gompertz law
  The estimation of the solution of a system of two differential equations introduced by Norton (1976) that is equivalent to the Gompertz law is performed by means of the recent adaptive scheme of Besancon and collaborators (2004). Results of computer simulations illustrate the robustness of the approach 
V. Ibarra-Junquera, M.P. Monsivais, H.C. Rosu, R. Lopez-Sandoval