A Brief History of Time and Calendars MacTutor History of At what time was the calendar created?
When did the calendar first introduced?
In which period did the agenda come into existence?
At what time was the calendar firstly devised?
In which period was the agenda firstly envisioned?
When was the schedule firstly introduced?
In what period was the schedule inception?
During what period did the calendar come about for the first time?