Columbia subject headings:
Harvard subject headings:
Bulbs (Plants)--Germany--History--20th century.
Flowers--Color--Germany--History--20th century.
Gardening--Germany--History--20th century.
Gardens--Design--History
Gardens--Germany--History--20th century.
Parks--Germany--History--20th century.
Perennials--Germany--History--20th century.
Princeton subject headings:
Bulbs (Plants)--Germany--History--20th century.
Flowers--Color--Germany--History--20th century.
Gardening--Germany--History--20th century.
Gardens--Design--History.
Gardens--Germany--History--20th century.
Parks--Germany--History--20th century.
Perennials--Germany--History--20th century.