folklore popular legend folk legend
legend in counter-legend
Carboniferous Period—Permian Period
Demand charge shift from the on-peak period to the off-peak period
middle_period and last_period state_mines
Paleogeng Period-Neogene Period
period shut-down (period trip)
period-to-period value changes
Spring and Autumn period and Warring States period
the Spring and Autumn Period and the Period of War
a legend created in the Tang Dynasty