<http://www.leyesyjurisprudencia.com/2015/02/uso-de-email-en-la-convocatoria-de.html>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.leyesyjurisprudencia.com/2015/02/uso-de-email-en-la-convocatoria-de.html>