Studies of Natural Soil Radioactivity in the Kirchhoff Hill (the Leningrad Region, the Russian Federation)S. V. Lebedev, I. I. Podlipskiy, S. V. Dubrova, P. S. Zelenkovskiy and S. G. KamenkovaE3S Web Conf., 285 (2021) 06006DOI: https://doi.org/10.1051/e3sconf/202128506006