<https://secure.gravatar.com/avatar/d1b9124ee8feca59c1d0ceb785c7878a?s=96&amp;d=mm&amp;r=g>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://bricoestilo.net/que-es-el-cilindro-de-la-cerradura/>