《新唐书·本纪·卷二·太宗》
同年八月初九，太宗在东宫显德殿登皇帝位。
八月甲子，即皇帝位于东宫显德殿。
On the ninth day of the first month of the eighth month of the same year, Taizong ascended to the throne of emperor in the Xiende Hall of the East Palace.