A few postcards and a letter remain that Isaac Hollander (known as Ies) sent his parents from Mauthausen and Buchenwald.
Jewish Historical Museum, Documents collection, inv.nr 6100 t/m 6102
In addition, a Jokos file (number 31801) on this household is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.
De briefkaart die Isaac Hollander vanuit Buchenwald stuurde is hier te lezen: http://bit.ly/1U6zUtz .
De briefkaart uit Mauthausen is hier te zien: http://bit.ly/1JmtM8A .