Niedźwiedzki, R., Surmik, D., Chećko, A. and Salamon, M.A. 2021. A regurgitalite of the Middle Triassic (Muschelkalk) from Upper Silesia (Poland). Geology, Geophysics and Environment. 47, 1 (Apr. 2021), 33–40. DOI:https://doi.org/10.7494/geol.2021.47.1.33.