https://en.wikipedia.org/wiki/Heshang_Gong
https://baike.baidu.com/item/%E6%B2%B3%E4%B8%8A%E5%85%AC
https://baike.baidu.com/item/%E9%81%93%E5%BE%B7%E7%9C%9E%E7%BB%8F%E6%B3%A8/6096608?fromtitle=%E6%B2%B3%E4%B8%8A%E5%85%AC%E7%AB%A0%E5%8F%A5&fromid=7651548
http://ccs.ncl.edu.tw/chinese_studies_18_2/18_2_04.pdf
https://www.amazon.com/Two-Visions-Way-Commentaries-Philosophy/dp/0791404560