《晋书·志·第一章》
这以后中垒校尉刘向扩展了《洪范》一书中关于灾害规律的记载，编著了《皇极论》，用来参考往昔所经历的事件。
其后中垒校尉刘向，广《洪范》灾条，作《皇极论》，以参往之行事。
After that, Liu Xiang, the lieutenant of the Central Guard, expanded the record of disaster laws in the "Hong Fan" book, and compiled the "Theory of the Royal Pole" as a reference for past events.