1. Foulds, L.: Amer. J. Cancer 35, 363 (1939).
2. Jacobson, L. E., and D. Rosenbaum: Radiology 31, 601 (1938).
3. MacMahon, H. E., A. S. Murphy and M. J. Bates: Amer. J. Path. 23, 585 (1947).
4. Rössle, R.: Zbl. Path. 85, 227 (1949).
5. Birkner, R.: Strahlenther. 78, 587 (1949).