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[1]E. V. Kasparyan, R. V. Medvedev, V. V. Zhukov, and E. V. Chernov, “Study of geologic structure, mechanical properties and state of rocks of mineral deposits for forecasting stability of mined-out spaces and protection of the day surface”, PMI, vol. 70, no. 2, pp. 120-125, Feb. 1976.