<http://0.gravatar.com/avatar/94ae0aea38fa6f1e70612225a4911b16?s=96&amp;d=mm&amp;r=g>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://trabajo-cooperativo.net/2019/12/17/resumen-practica-4-de-programacion/>