1. Vedere le bibliografia data da:H. Yagoda:Radioactive Measurements with Nuclear Emulsions (New York, 1949).
2. V. I. Baranov eS. I. Kretschmer:Compt. Rend. Acad. Sci. U.R.S.S.,1, 543 (1935).
3. I. Curie:Journ. Phys. Rad.,7, 313 (1946).
4. R. Coppens:Bull. Soc. Franc. Min. Crist.,73, 217 (1950).
5. A. Hee:Compt. Rend.,227, 356 (1948).