Assessment of parting rock weak zones under the joint and downward mining of coal seamsVolodymyr Bondarenko, Iryna Kovalevska, Hennadii Symanovych, Mykhailo Barabash and Vasyl SnihurE3S Web Conf., 66 (2018) 03001DOI: https://doi.org/10.1051/e3sconf/20186603001