How to check if someone is referencing the dll?

In my work we have an outside bin library which has many many dll's.

they want to clean it up. (remove unu开发者_Go百科sed dlls)

out solution has many many projects.

what is the best way to check if a dll is referenced without iterating each project ?

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NDepend creates a nice reference graph

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Since for some reason this question is tagged ReSharper, I should note that ReSharper 6.1 (early access for this new version is coming soon) is expected to introduce a feature to find and remove unused assembly references