SI-bureau in Vienna. Kéthly (second from the left) and Helmer (third).

SI-bureau in Vienna. Kéthly (second from the left) and Helmer (third).

SI-bureau in Vienna. Kéthly (second from the left) and Helmer (third).

SI-bureau in Vienna. Kéthly (second from the left) and Helmer (third).