Anton Ivanov. "ANALYSIS OF 90 YEARS SEA LEVEL DATA AT VARNA TIDE GAUGE STATION." SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings; 19th International Multidisciplinary Scientific GeoConference SGEM2019, Informatics, Geoinformatics and Remote Sensing (2019): 11-16. https://doi.org/10.5593/sgem2019/2.2/s09.002