How to access Application.Resources resource by it's name?

Question

<x:Array x:Name="NBresource" x:Key="nb" Type="{x:Type System:String}">
<System:String>10</System:String>
<System:String>15</System:String>
<System:String>20</System:String>
</x:Array>
In my application.Resources I have got an Array. In the code behind MainWindow I am trying to access this array but I don't find any way in doing so using it's name only? 
If I would have defined the resources in the MainWindow.xaml, I could easily access it using it's name only. 

Answer 1

>>The Resources property of both the Application class and the Window class is of type ResourceDictionary and ResourceDictionary
is a class that implements the IDictionary interface. This interface includes an [] operator that lets you access an element by its key and
nothing else.
If I would define it like this:
<Window.Resources>
<x:Array x:Name="NBresource" x:Key="nb" Type="{x:Type sys:String}">
<sys:String>10</sys:String>
<sys:String>15</sys:String>
<sys:String>20</sys:String>
</x:Array>
</Window.Resources>
Then it would have been possible to get the values like this:
PipeSizeNTD_comb.ItemsSource = NBresource.Items;
I was using it with its name, but now I want to move it from Window.Resources to Application.Resources so that it would be available to
the whole application and it's not possible to use its name.