<https://nuraabdelfattah.com/blog/2020/03/07/%d9%84%d8%a7-%d8%aa%d9%81%d8%b9%d9%84/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://nuraabdelfattah.com/blog/2020/03/07/%D9%84%D8%A7-%D8%AA%D9%81%D8%B9%D9%84/>