【More・・・】
In which period was the agenda originated?
In what period did the calendar first developed?
During what period did
the calendar arise?
When did the timetable originally devised?
During what period did the calendar originally thought up?
In what period did the agenda firstly created?
In which period was the timetable inception?
During what period did the calendar emerge for the first time?
Keeping time The origin of BC and AD