<https://coolwebfun.com/on-page-seo-checklist/on-page-seo-9/#primaryimage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://schema.org/ImageObject>
<https://coolwebfun.com/on-page-seo-checklist/on-page-seo-9/>