R. P. Sánchez Figueredo, A. B. G. Domínguez, R. P. Rodríguez, and F. H. Oviedo Fierro, “Increase of the General Technological Yieldin the Securing of Gray Iron with Graphite Spheroidal for the Metódo of Spilled Vibratory”, ijsei, p. 102 to 109, May 2016.