According to the "Sterbebücher" (death records) of Auschwitz, Jacob Coster was murdered there on 31 August 1942. This date is different from the official date of death as determined by the Dutch Ministry of Justice after the war. For the time being, the website joodsmonument.nl, list only the dates of death, as published at the time in the "Nederlandse Staatscourant" (Dutch Government Gazette) by the Ministry of Justice.
Sterbebuch Auschwitz (death record)
Official death certificate nr. 1950/1530 for Jacob Coster dated 30 June 1950