This class contains a reference to a RibbonPanelSource.

Autodesk.AutoCAD.Customization.ElementBase
    Autodesk.AutoCAD.Customization.VersionableElement
        Autodesk.AutoCAD.Customization.CustomizationElement
            Autodesk.AutoCAD.Customization.RibbonItem
                Autodesk.AutoCAD.Customization.RibbonPanelSourceReference

Public Class RibbonPanelSourceReference
Inherits RibbonItem

public class RibbonPanelSourceReference : RibbonItem;