<https://secure.gravatar.com/avatar/681e07920401b1bd219fb597b452355e?s=96&d=mm&r=g>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://kryptoszene.de/news/deutsche-boerse-erlaubt-wohl-bald-den-bitcoin-handel/>