"1987Z"^^ . "Berger, Dionys"@en . "1987-04-19Z"^^ . "Dionys Berger (10 July 1892, Amsterdam - 19 April 1987) was a Dutch secondary school physics teacher and author of the novel Sphereland."@en . "Dutch mathematician" . . "1892Z"^^ . "1892-07-10Z"^^ .