Ureña, A., J. Ramos, F. J. Méndez, and J. Rodríguez. “Environmental Management and Educational Needs of the Small and Medium-Sized Businesses of the Metallurgical Sector in the South Region of Madrid”. Revista De Metalurgia, vol. 40, no. 3, June 2004, pp. 209-13, doi:10.3989/revmetalm.2004.v40.i3.266.