<https://articles.ibpa-online.org/%ed%9b%a8%ec%94%ac-%eb%8d%94-%ec%a0%95%ed%99%95-%ed%95%b4%ec%a7%80%ea%b3%a0-%ed%83%80%ec%9e%84-%eb%9d%bc%ec%9d%b8-%eb%b3%80/#breadcrumb>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://articles.ibpa-online.org/%ED%9B%A8%EC%94%AC-%EB%8D%94-%EC%A0%95%ED%99%95-%ED%95%B4%EC%A7%80%EA%B3%A0-%ED%83%80%EC%9E%84-%EB%9D%BC%EC%9D%B8-%EB%B3%80/>