Columbia subject headings:
Harvard subject headings:
Middle class--Germany--History
Social norms--Germany--History.
Time management--Germany--History.
Time perception--Germany--History.
Time--Social aspects--Germany--History.
Princeton subject headings:
Middle class--Germany--History.
Social norms--Germany--History.
Time management--Germany--History.
Time perception--Germany--History.
Time--Social aspects--Germany--History.