In which period was the schedule invented?
During what period was the schedule first developed?
At what time was the schedule come into existence?
At what time did the agenda initially created?
In which period did the agenda originally envisioned?
In what period did the agenda firstly devised?
In which period was the calendar inception?
In which period did the timetable come about for the first time?
Maya calendar Wikipedia
- 04/13/01:39
- Exploring the history and evolution of Advent calendars NPR
