《汉书·传·外戚传下》
建昭年间，元帝到虎圈观看斗兽，后宫都坐在一旁。
建昭中，上幸虎圈斗兽，后宫皆坐。
In Jianzhao era, Emperor Yuan went to the beast fighting enclosure to watch the beasts’ fight, with all the people from the harem sitting on the side.