"Das Bundesarchiv". Kabinettsprotokolle Online "Barth, Siegfried" (2.26:) (بالألمانية). Archived from the original on 2017-01-01. Retrieved 2013-06-11.
"Das Bundesarchiv". Kabinettsprotokolle Online "Barth, Siegfried" (2.26:) (بالألمانية). Archived from the original on 2017-01-01. Retrieved 2013-06-11.