LetterArquivado em 2014-02-28 no Wayback Machine Margarete Oldenburg to Heidi Teckenberg from 1 October 1976 at the Kaupisch family website. (Retrieved 24 February 2014).
LetterArquivado em 2014-02-28 no Wayback Machine Margarete Oldenburg to Heidi Teckenberg from 1 October 1976 at the Kaupisch family website. (Retrieved 24 February 2014).