<http://schema.org/keywords>
"\u30C6\u30B9\u30E9\u30FB\u30E2\u30FC\u30BF\u30FC\u30BA"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.huffingtonpost.jp/2016/07/04/teslas-difficult-month_n_10807694.html>