SGEM 2020. 20th International Multidisciplinary Scientific GeoConference. Volume 20. Science and Technologies in Geology, Oil and Gas Exploration, Water Resources, Forest Ecosystems : conference proceedings. 8-11 December 2020, Vienna, Austria. Issue 1.3 Hydrology and Water Resources. 1. vyd. Sofia : STEF 92 Technology, 2020. 870 s. ISBN 978-619-7603-17-0. ISSN 1314-2704.