<https://secure.gravatar.com/avatar/7c3ddfc164c1da6569411d56e5d20179?s=96&amp;d=wavatar&amp;r=g>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://no-black-box-seo.de/en/blog/offpage-seo/youtube-seo/>