Periodicals
- Technische Rundschau
- Letter from: 25.5.1917, Oberammergau (Germany)
- The Observer <London>
- Letter from: 26.1.1936, Zurich (Switzerland)
- Letter from: 5.7.1936, London (England)
- The Times <London>
- Letter from: 29.12.1934, Milan (Italy)
- Letter from: 13.8.1937, London (England)
- Letter from: 6.9.1937, Saint Moritz (Switzerland)
- Letter from: 24.6.1938, London (England)
- Letter from: 29.9.1938, Penrhyndeudraet /North Wales
- The Times <New York>
- Letter from: 21.00.1950 [21.10.1950?], o.O. [Ojai (Calif.)?]
- Times Magazine <New York>
- Letter from: o.D. [1949?], San Francisco (Calif.)