Ochmann, A. A. “Distribution of Radon Activity in the Atmosphere above Wzgórza Niemczansko-Strzelinskie (South-WestPoland) and Its Dependence on Uranium and Thorium Content in the Underlying Rock and Indirect Ground Basement”. Annals of Geophysics, vol. 48, no. 1, Dec. 2005, doi:10.4401/ag-3186.