1. Electrical conductivity in the troposphere;Callahan;J. Geophys. Res.,1951
2. Research on the radioactivity of free air;Garrigue;C.-R., Paris,1951
3. Radioactivity of the atmosphere;Israel,1951
4. Some measurements of vertical diffusion in the free atmosphere;Machta,1951
5. Schmidt, W., , Der Massenaustausch in freier Luft und verwandte Erscheinungen, Hamburg, 1925,