How to: A ListBox from two sources?

I am using EF with WPF.
How should I create a ListBox that shows both Contacts and Persons?
My question is rather how to retrieve it and create the CollcetionViewSource(s).

I know I will have to use ItemTemplateSelector, that's less what I care, what I really care is the retrieval, but any tips on the representation will be welcommed as well.

Thanks

From stackoverflow Shimmy

• See the CompositeCollection class.

  HTH,
  Kent

  Shimmy : WOW, I thought the solution is much more complex! Thanks!!
  From Kent Boogaart