Exploring the history and evolution of Advent calendars NPR
At what time was the agenda created?
In which period did the calendar first introduced?
During what period was the calendar come into existence?
At what time was the calendar firstly invented?
During what period did the timetable originally imagined?
At what time was the agenda firstly established?
During what period was the calendar generation?
In which period was the calendar emerge for the first time?