<https://architettoclub.it/21-errori-fatali-2nd-edition/sample-optin/oto-1/optin/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://architettoclub.it/21-errori-fatali-2nd-edition/sample-optin/oto-1/optin/>