<https://secure.gravatar.com/avatar/6194eb9b33fea2fd25d75097e4c77161?s=96&d=mm&r=g>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.expo2005.cz/naucte-se-pracovat-s-tabulkovym-editorem-v-pohodli-domova-2/>