《旧五代史·后梁·末帝纪下》
夏四月二十五日，晋王在魏州建立后唐国号，并即帝位，改天二十年为同光元年。
夏四月己巳，晋王即唐帝位于魏州，改天祐二十年为同光元年。
On the 25th day of the fourth month of summer, the King of Jin established the state of Later Tang and took the imperial throne in Wei Prefecture, renaming the 20th year of Tianyou as the 1st year of Tongguang.