Ziegelwelt : Deutsche Töpfer- und Ziegler-Zeitung
- 56.1925 New York-USA* = Google-USA*
- 57.1926 New York-USA* = Google-USA*
- 58.1927 New York-USA* = Google-USA*
- 59.1928 New York-USA* = Google-USA*
- 60.1929 New York-USA* = Google-USA*
- 61.1930 New York-USA* = Google-USA*
- 62.1931 New York-USA* = Google-USA*
- 63.1932 New York-USA* = Google-USA*
- 64.1933 New York-USA* = Google-USA*
- 65.1934 New York-USA* = Google-USA*