1. S. Körner:Observation and Interpretation (London, 1957).
2. M. Planck:Scientific Autobiography (London, 1950), pp. 121–150.
3. A. Einstein:Out of My Later Years (New York, 1950). pp. 85–93 and 106–110.
4. L. de Beoglie:Nuovo Cimento,1, 37 (1955).
5. E. Schrödinger:Nuoro Cimento,1, 5 (1955).