Стеценко, В.В. and Зайченко, В.В. 2019. Study of mineralogical variability of ferruginous quartzites of productive strata of the eastern wing of the Petrovsky synclinal fold with using diagram Mm-Mo. Visnyk of V. N. Karazin Kharkiv National University, series "Geology. Geography. Ecology". 50 (Jul. 2019), 54-62. DOI:https://doi.org/10.26565/2410-7360-2019-50-04.