QuickAccessToolBar RibbonGroup ResourceDictionary

Question

Hello! Who knows how write xaml-file. In this file I'd like describe list Buttons that will use in QuickAccessToolBar and RibbonGroup.

<!--First file-->
        <r:RibbonTab>
           <r:RibbonTab.Resources>
                <ResourceDictionary>
                    <ResourceDictionary.MergedDictionaries>
                        <ResourceDictionary Source="SourceCommands.xaml"/>
                    </ResourceDictionary.MergedDictionaries>
                </ResourceDictionary>

        <r:RibbonGroup Name="coolectionButtons" Command="{}"> 
        <SourceButtons.xaml> --------- ??????????????????? how include?
        </r:RibbonGroup>

<!--Second file-->

    <r:RibbonWindow>
       <r:RibbonWindow.Resources>        
            <ResourceDictionary>              
                <ResourceDictionary.MergedDictionaries>            
                    <ResourceDictionary Source="SourceCommands.xaml"/>
                </ResourceDictionary.MergedDictionaries>           
            </ResourceDictionary>
       </r:RibbonWindow.Resources>
       <r:Ribbon.QuickAccessToolBar>
                    <r:RibbonQuickAccessToolBar>  
              <SourceButtons.xaml> --------- ??????????????????? how include?
         </r:RibbonQuickAccessToolBar>
       </r:Ribbon.QuickAccessToolBar>
    </r:RibbonWindow>

<!--Third file-->

SourceButtons.xaml - what need I write in this file?