ANDRÁSSY, E., MOJZEŠ, A., NOGOVÁ, E. and ČANGEL, O. 2021. Surface identification of undermined spaces with the use of soil radon emanometry. Contributions to Geophysics and Geodesy. 51, 2 (Jun. 2021), 189-205. DOI:https://doi.org/10.31577/congeo.2021.51.2.5.