<https://www.docmckee.com/WP/oer/statistics/section-1-basic-concepts/section-1-5/#breadcrumb>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.docmckee.com/WP/oer/statistics/section-1-basic-concepts/section-1-5/>