Part of Papers of Otto Frisch
American Physical Society, M.I.T., April 1946.
The Physical Society, Conference on Fundamental Particles and Low-Temperature Physics, Cambridge, July 1946.
University of Ghent Colloquium, invitation and letter of thanks from A. Berthelot, 1946-47.
Collège de France, Rutherford memorial meeting, 1947.
University of Birmingham, Conference 'Problems of Nuclear Physics', September 1948.