<https://zh.coursera.org/pku#institution>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://zh.coursera.org/lecture/dmathgen/02-zheng-shi-nei-rong-zhi-qian-xing-shi-hua-ji-qi-ji-xian-oU1eN?authMode=login>