Avramova, N. .; Mihaylova , I. .; Yaneva-Ribagina, K.; Bonev , B.; Nenov , S. DENTAL STUDENTS’ PERSPECTIVES ON THE IMPLEMENTATION AND EFFECTIVENESS OF ONLINE LEARNING DUE TO COVID-19 PANDEMIC: A DESCRIPTIVE CROSS-SECTIONAL STUDY IN BULGARIA. Adv Educ 2021, 8, 109-118.