If you use ReSharper, you can right-click the Links folder and select Delete Unused Links or the safer option to Optimize Links. The latter option gives you a report on which assemblies are and are not used.
Use caution when using this in a mature solution where dependencies are injected, as you may not have links to direct assembly references at compile time. But they may be required during operation.
Sorry, I did not answer your question directly, but I hope I showed you how to find out for myself.
Daniel Dyson
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