Multiple applications sharing code offline

I am developing two windows desktop applications, one with a GUI and one without. (In visual studio 2013, c#) These applications are using very similar code and would like to know if and how they can share it.

I've looked at project references but feel like the client would have to specify search paths for a shared class library in order to have the applications find the shared code when installed. The applications will run offline.

Clarification; Application A & B share code. When installing both applications (offline), these need to share code without the user having to bother with linking to a shared-code-project. This project or class library would need to somehow be installed together with an application.

Easiest solution I can think of is simply duplicating the code which I'm obviously trying to avoid