Miroslav Кrastanov, Rosen Nankin, Plamen Ivanov. "GEOTECHNICAL INVESTIGATION AND SPATIAL ORIENTATION OF THE SEDIMENTS OF THE TOPOLA FORMATION IN THE AREA OF THE TOPOLA VILLAGE LANDSLIDES, NORTHEAST BULGARIA." SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings; 20th SGEM International Multidisciplinary Scientific GeoConference Proceedings 2020, Science and Technologies in Geology, Exploration And Mining (2020): 547-552. https://doi.org/10.5593/sgem2020/1.1/s02.067