His published university lectures in theoretical physics. Part 1. Stralingstheorie (1910–1911, Radiation theory) in Dutch, edited by his student A. D. Fokker, 1919.
Photograph of the first conference, 2 November, 1911, at the Hotel Metropole Seated (L–R): W. Nernst, M. Brillouin, E. Solvay, H. Lorentz, E. Warburg, J. Perrin, W. Wien, M. Skłodowska-Curie, and H. Poincaré. Standing (L–R): R. Goldschmidt, M. Planck, H. Rubens, A. Sommerfeld, F. Lindemann, M. de Broglie, M. Knudsen, F. Hasenöhrl, G. Hostelet, E. Herzen, J. H. Jeans, E. Rutherford, H. Kamerlingh Onnes, A. Einstein and P. Langevin.