Matthias Ritzi; Erich Schmidt-Eenboom (2011), Ch. Links Verlag (ed.), Im Schatten des Dritten Reichs. Der BND und sein Agent Richard Christmann (in German), Berlin, pp. 1–50{{citation}}: CS1 maint: location missing publisher (link)
René Caboz[in French] (1984), Éditions Pierron (ed.), La bataille de Metz, Sarreguemines, p. 132{{citation}}: CS1 maint: location missing publisher (link).
