The Advent calender printed by Gerhard Lang in 1908, had what?

Explanation

The origins of the Advent calendar come from German Lutherans who, at least as early as the beginning of the 19th century, would count down the 24 days of Advent physically. Gerhard Lang printed a calendar, in 1908, with 24 little colored pictures that could be affixed to a piece of cardboard. Several years later, he introduced a calendar with 24 little doors.