Dżaluk, Agnieszka, Dariusz Malczewski, Jerzy Żaba, and Maria Dziurowicz. 2015. “Laboratory Measurements of Natural Radioactivity in Selected Igneous Rocks of the Opava Mountains Region”. Geology, Geophysics and Environment 41 (1):73. https://doi.org/10.7494/geol.2015.41.1.73.