《北史·列传·卷二十三》
得胜的是白龙，因为杨姓按照五音应当是商，皇上又是辛酉年所生，方位都在西方，西方是白色。
胜龙所以白者，杨姓纳音为商，至尊又辛酉岁生，位皆在西方，西方白色也。
The white dragon won because the Yang surname should be Shang according to the five tones, and the emperor was born in the year of Xinyou, and the direction was in the west, and the west is white.