<https://challenge-juku.com/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://challenge-juku.com/juniorhighschool/%E4%B8%AD2%E7%94%9F%E3%82%B3%E3%83%BC%E3%82%B9_%E6%AE%8B%E5%B8%AD%E3%81%82%E3%82%8A-3/>