《旧唐书·本纪·卷十八》
敕令以河阳三城镇遏使治理孟州，割取泽州隶属于它，合怀州、孟州、泽州为一个节镇，号称河阳。
敕以河阳三城镇遏使为孟州，割泽州隶焉，与怀、孟、泽为节度，号河阳。
The edict commanded to use the three cities of Heyang to suppress governance in Mengzhou, and to appropriate Zezhou under its control, bringing Huaizhou, Mengzhou and Zezhou together as one garrison, called Heyang.