<https://www.shipfriends.gr/forum/topic/7822-%CE%BC%CF%85%CF%84%CE%B9%CE%BB%CE%AE%CE%BD%CE%B7-%CE%AE-%CF%81%CE%BF%CE%B4%CE%AC%CE%BD%CE%B8%CE%B7/#comment-318031>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.shipfriends.gr/forum/topic/7822-%CE%BC%CF%85%CF%84%CE%B9%CE%BB%CE%AE%CE%BD%CE%B7-%CE%AE-%CF%81%CE%BF%CE%B4%CE%AC%CE%BD%CE%B8%CE%B7/>