References

All the external references for a project can be seen under the References node
If you cannot see the References node then you need to "show all files" for that project.
SS
You can write code against external components by adding references to your project.
To remove a reference right click on that particular reference and select Remove

Types of References

File References
Project References

When you choose Add Reference you will see the Reference Manager dialog box.
SS

.NET tab	.NET Framework class libraries and assemblies
COM tab	COM components
Project tab	Project to Project class libraries and assemblies. These are references to projects that contain assemblies. This will create a dependency when the project is built
Browse tab	This is for individual file references. This can be used to add references that were in the GAC and are then copied locally to be included into a Setup project.
Recent tab

Adding References

To add a reference right click and select Add a Reference
VSTO projects behave slightly differently to regular class libraries and for that reason will not appear in this list.
To add a reference to a VSTO project you need to choose the Browse tab and select the most recent version of that dll in the bin folder.

Properties

SS - properties windows, when selecting a reference dll
Aliases - A comma delimited list of aliases applied to this reference.
Copy Local - Indicates whether the reference will be automatically copied to the "build output path" folder at runtime.
At run-time references must be either in the GAC or in the build output path of the project.
By default this is set to False for assemblies in the GAC and for framework components.
For all other references this is set to True by default.
Any dependencies that a reference has will also be copied to the build output path

Culture - The value of the culture field from the assembly metadata.
Description - The value of the Title field from the assembly metadata.
Embed Interop Types - Indicates whether types defined in this assembly will be extended into the target assembly. One limitation is that classes cannot be used once an assembly has been embedded. If you try to reference a class type from an Interop assembly which has this option set you will get a compilation error message
File Type - The file type of the reference. Either Assembly, ActiveX or Native Assembly.
Identity - Security identity of the referenced assembly (System.Reflection.Assembly or System.Security.Policy.Evidence)
Path - Location of the file being referenced
Resolved - Indicates whether the reference was successfully resolved.
Runtime version - Version of the .NET runtime this assembly was compiled against.
Specific version - Indicates whether this assembly can be resolved without regard to multi-targeting rules for assembly resolution. This is a build setting and not a deployment setting. It will just use the latest version of the assembly when it performs a build. At runtime the framework will still look for the specific version that was used at build time. If you want to update the version of a dependent dll this can be achieved using Publisher Policy.
Strong name - True indicates that the reference has been signed with a key-pair
Version - Version of the referenced.

VB.NET

The References node is not displayed by default in the Solution Explorer
This can be seen by clicking on the 'Show All Files' icon at the top
These references are also displayed on a tab on the Properties dialog box