<https://secure.gravatar.com/avatar/884c103e68f8ec53e7925b9d1355ed95?s=96&amp;d=mm&amp;r=g>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://bangtaivietnam.vn/dac-diem-cua-he-thong-bang-tai-say.html>