sentences:  The fit of a line using the data points from 1956 to 2005 (in green) gives a URR of 199 Gb and a logistic growth rate of 6%.The Norwegian Hubbert linearization estimates an URR = 30 Gb and a logistic growth rate of k = 17%.The Hubbert linearization principle can be extended to the first derivatives of the production rate by computing the derivative of (2)