Kalla, S. L., and L. Viloria. “A Note On: Fenyo, A., and Frey, T., Modern Mathematical Methods in Technology, Vol. 1, North-Holland Publishing Company, Amsterdam, 1969”. Rev. Téc. Fac. Ing. Univ. Zulia, Vol. 1, no. 1, 1, http://www.produccioncientifica.luz.edu.ve/index.php/tecnica/article/view/3876.