《后汉书·本纪·光武帝纪下》
孝宣帝每当有吉祥的现象出现，便根据祥瑞改纪元，神爵、五凤、甘露，黄龙列为年号，大概是用它们感谢神祗，表彰自己的德行和诚信。
孝宣帝每有嘉瑞，辄以改元、神爵、五凤、甘露、黄龙，列为年纪，盖以感致神祇，表彰德信。
Whenever a lucky sign appeared, Emperor Xiao Xuan would alter the era-name according to the good omen; he called the era-names Shen Jue, Wu Feng, Gan Lu, and Huang Long to probably thank the gods and show his virtue and faith.