<https://secure.gravatar.com/avatar/6081181fc6dc34553a287f7a6bf3799d?s=96&amp;d=mm&amp;r=g>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.bba.edu.rs/predavanje-prof-miguela-angela-adamea/>