Given a topological space **X** and a finite cover **X** = $\cup X\_i$, one can define Cech cohomology of a sheaf of abelian groups **F** with respect to the cover $\{X\_i\}$ in two different ways: 


1. (Ordered): The kth term of the Cech
 complex is $\bigoplus\_{i\_1 < \ldots
 < i\_k} \Gamma(X\_{i\_1} \cap \ldots
 \cap X\_{i\_k}, F)$.
2. (Unordered): The kth term of the Cech
 complex is $\bigoplus\_{i\_1, \ldots
 , i\_k} \Gamma(X\_{i\_1} \cap \ldots
 \cap X\_{i\_k}, F)$.


In particular, the second description involves repetition and is non-zero in every degree. These two descriptions give isomorphic cohomology (the first maps you try to write down will likely be homotopy equivalences). 




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**Question**: Is there a canonical reference for this fact?



Equivalence of ordered and unordered cech cohomology. 
I wrote it up for my algebraic geometry course as a 2-page [handout](http://math.stanford.edu/~conrad/papers/cech.pdf), inspired by EGA $0\_{\rm{III}}$, 11.8.7 (which isn't to say this is a canonical reference; just some written reference...).


