2017年04月 / Keeping time The origin of BC and AD
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During what period was the timetable invented?
When was the calendar first introduced?
During what period was the agenda emerge?
At what time did the schedule firstly devised?
In which period was the schedule originally thought up?
During what period was the calendar firstly created?
At what time was the timetable creation?
In what period did the schedule come about for the first time?