Issues of the Preservation and Conservation of the Petroglyph in the Khoid Tsenkher CaveKhishigdalai Ulaankhuu, Bat-Erdene Nyandag and Avirmed Erdene-DalaiE3S Web Conf., 251 (2021) 03039DOI: https://doi.org/10.1051/e3sconf/202125103039