His brother - in - law and fellow Constructivist promoter was the writer Jacques G. Costin , known as a survivor of 1940s antisemitism .
Marcel Janco was the brother of Georges and Jules Janco , who were his artistic partners during and after the Dada episode .
Marcel Janco 's brother - in - law and fellow Constructivist promoter was the writer Jacques G. Costin , known as a survivor of 1940s antisemitism .
Marcel Janco was the brother of Georges and Jules Janco , who were his artistic partners during and after the Dada episode .