How to fix an error when downloading a package from Nuget?

Question

Unit testing

I'm trying to install xUnit from Nuget in Visual Studio 2013 and I'm catching an error:

Attempting to resolve dependency 'xunit.core (= 2.3.1)'. Attempting to resolve dependency 'xunit.extensibility.core (= 2.3.1)'. Attempting to resolve dependency 'xunit.extensibility.execution (= 2.3.1)'. Attempting to resolve dependency 'xunit.assert (= 2.3.1)'. Attempting to resolve dependency 'xunit.analyzers (≥ 0.7.0)'. Child dependencies of dependency only packages cannot mix external and project packages.

What can I do to successfully install the package?
I thought that VS has some settings for this, but some of them are poor for Nuget Packet Manager in VS 2013