1. Galois theory and cohomology of commutative rings;Chase;Mem. Amer. Math. Soc.,1968
2. Galois extensions as modules over the group ring;Garfinkel;Canad. J. Math.,1970
3. SGA1;Grothendieck,1971
4. SGA4, Exposé VII;Grothendieck,1972
5. Separable algebras over commutative rings;Janusz;Trans. Amer. Math. Soc.,1966