Repstock, A. Voudouris, P. Zeug, M. Melfos, V. Zhai, M. Li, H. Kartal, T. Matuszczak, J., Chemical composition and varieties of fahlore-group minerals from Oligocene mineralization in the Rhodope area, Southern Bulgaria and Northern Greece, Mineralogy and Petrology, (110), 103-123, 2016, Springer-Verlag Wien, 0930-0708