Sharing projects across multiple solutions

I have a very big solution right now (> 100 projects), and want to split it into several smaller solutions to speed up loading and build time.
All projects are checked in to SourceSafe.

If I create an empty solution, I can move the necessary projects to the new folder. But what about the dependent projects that need to be shared across all solutions For example:


Monolithic solution
+ Common classes solution
+ Common controls solution (references common classes)
+ Project 1 (references common classes)
+ Project 2 (references common classes and common controls)


That the way it is now. Here's what I have in mind:

Shared parts solution
+ Common classes
+ Common controls

Project 1 solution
+ Project 1

Project 2 solution
+ Project 2


Of course, any changes to the common classes should be reflected in all projects, so I would need to set some kind of project reference. Is this possible Any help is welcome.