佛祖歷代通載 7.86

7.86

後燕高雲（字子羽。惠文熙之長子。自云高陽之後。因以為姓。熙死僭立一年。改國曰大燕。年改正始）。

Gao Yun of Later Yan (courtesy name Ziyu, eldest son of Emperor Huiwen, Murong Xi; he claimed to be a descendant of Gaoyang and took that as his surname. When Murong Xi died, he usurped the throne for one year, changed the state name to Great Yan, and changed the reign era to Zhengshi).