Krstić, B., Maslarević, L., & Sudar, M. (2005). On the graptolite schist’s formation, Silurian-Lower Devonian, in the Carpatho-Balkanides of eastern Serbia. Geološki Anali Balkanskoga Poluostrva, 66(1), 1-8. https://doi.org/10.2298/GABP0566001K