If you have Visual Studio 2012 installed, you will find specification somewhere there:
c:\Program Files (x86)\Microsoft Visual Studio 11.0\VC#\Specifications\1033\CSharp Language Specification.docx
similar with VS2013:
c:\Program Files (x86)\Microsoft Visual Studio 12.0\VC#\Specifications\1033\CSharp Language Specification.docx
VS2015:
c:\Program Files (x86)\Microsoft Visual Studio 14.0\VC#\Specifications\1033\CSharp Language Specification.docx