CybenkoG. (1987), ‘Approximations by superpositions of a sigmoidal function’, Mathematics of Control, Signals and Systems, 2, pp303–314. Gurumoorthy, A and Kosanovich, KA, (1998) ‘Improving the prediction capability of radial basis function networks’, Ind. Eng. Chem. Res., 37, pp.3956–3970.