Microsoft - Office Excel 12.0 Object Library Download [best]

Microsoft’s official stance is clear: type libraries are only available through Office installation media.

C:\Program Files (x86)\Microsoft Visual Studio\Shared\Visual Studio Tools for Office\PIA\Office12 Global Assembly Cache (GAC) C:\Windows\assembly\GAC_MSIL\Microsoft.Office.Interop.Excel Common Files microsoft office excel 12.0 object library download