# Cohomology of sheaves for sites and Galois cohomology

Hello,

I am looking for a reference (if it exists) that makes the link between cohomology of sheaves for sites and Galois cohomology :

quickly said, I would like to see Galois cohomology (at least in the commutative case) as the cohomology of a sheaf over the étale site of extensions of k.

By the way, what is a reference for cohomology of sites ?

Thanks

• Milne's notes on étale cohomology. Tamme's book on étale cohomology. – Mariano Suárez-Álvarez Mar 1 '10 at 15:24
• Both of Mariano's references are good. Also, there's plenty of lectures notes and unofficial write-ups of this material all over the web. For example, try googling "mcgill seminar on cohomology" (no quotes). – Cam McLeman Mar 1 '10 at 15:37

The two references from my comment above, now with links!

• Milne, James S. Étale cohomology. Princeton Mathematical Series, 33. Princeton University Press, Princeton, N.J., 1980. xiii+323 pp. MR0559531 You can get another set of notes on étale cohomology from his web page: «in comparison with my book, the emphasis is on heuristic arguments rather than formal proofs and on varieties rather than schemes».
• Tamme, Günter. Introduction to étale cohomology. Translated from the German by Manfred Kolster. Universitext. Springer-Verlag, Berlin, 1994. x+186 pp. MR1317816