visual studio 2012 - How to get reference Microsoft.VisualStudio.TeamFoundation.dll (version-11.0.0.0) -

visual studio 2012 - How to get reference Microsoft.VisualStudio.TeamFoundation.dll (version-11.0.0.0) -

i'm trying create visual studio 2012 add-in able hear various tfs version command events , perform custom actions prior or after events.but @ time running programme shows next error

[a]microsoft.visualstudio.teamfoundation.teamfoundationserverext cannot cast [b]microsoft.visualstudio.teamfoundation.teamfoundationserverext. type originates 'microsoft.visualstudio.teamfoundation, version=11.0.0.0, culture=neutral, publickeytoken=b03f5f7f11d50a3a' in context 'default' @ location 'c:\windows\microsoft.net\assembly\gac_msil

after research ,found microsoft.visualstudio.teamfoundation.dll (version-11.0.0.0) used resolve program.but how can add together version of dll project

we can reference next path

c:\windows\microsoft.net\assembly\gac_msil\microsoft.visualstudio.teamfoundation\v4.0_11.0.0.0__b03f5f7f11d50a3a\microsoft.visualstudio.teamfoundation.dll

visual-studio-2012 tfs