107. Urey had already given away the entire farm, so it was a little late to make the process a secret. In April 1941 Urey had published an extensive survey, “Separation and Use of Stable Isotopes,” in the Journal of Applied Physics, covering known methods of isotope separation with emphasis on gaseous diffusion. There was a stoppage of papers directly concerning fission, but peripheral issues were still being put into print. This important paper was definitely noticed by the Germans, who included it in the report Kernphysik Techn. Stand und Anwendungsmöglichkeiten assembled for Henschel Flugzeugwerke in August 1941.