I need the C#.net reference for Microsoft.Web.UI.WebControls

Working on some of the more legacy application's that were built for my organization. I need the reference Microsoft.Web.UI.WebControls which is not available from Microsoft to download. The app would be a pain to rewrite for a simple bug fix.

The app uses: TabStrip - Heavy usage, MultiPage - only a few instances.

Need the Microsoft.Web.UI.WebControls.dll to use as a reference.