Recently it was shown that some nonlinear second order differential equations could be linearized by a point transformation generated by the generator
are unknown coefficients. Because the set of all generators of a differential equation creates a Lie algebra under the operation of the Lie bracket it is interest in finding the number of generators for a system of differential equations. The paper in the heading deals with the mentioned problem for the system
, where a,b,c,d are constant coefficients. Some considerations are extended to higher dimensional systems. The case when a,b,c,d depend upon t is also discussed.