1. Artin, M.: On algebraic extensions of local rings. Rendiconti di Mathematica (1?2).25, 33?37 (1966).
2. Artin, M., Winters, G.: Degenerate fibers and stable reduction of curves. (To appear.)
3. Cassels, J.W.S., Fröhlich, A.: Algebraic Number Theory. Washington, D.C.: Thompson Book Co. 1967.
4. Cohen, I.S.: On the structure and ideal theory of complete local rings. Trans. Amer. Math. Soc.59, 54?106 (1946).
5. Hasse, H.: Die Gruppen der ? n Zahlen für einen Primteiler ? vonp. J. reine Angew. Math.162, 145?168 (1930).