Stefka Petrova. INFORMATION SYSTEMS USED IN BULGARIAN UNIVERSITY LIBRARIES AS ONLINE PUBLIC ACCESS CATALOGS. SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings; 19th International Multidisciplinary Scientific GeoConference SGEM2019, Informatics, Geoinformatics and Remote Sensing, 2019, pp. 353-360. https://doi.org/10.5593/sgem2019/2.1/s07.046