Simeonovski, Ivan, Viktoriya Levterova, Mariya Malcheva, and Todor Kantardjiev. 2018. “GENETIC SURVEY OF INVASIVE S. PNEUMONIAE SEROTYPES IN BULGARIA FOR A 5-YEAR PERIOD”. PROBLEMS of Infectious and Parasitic Diseases 46 (2):5-9. https://pipd.ncipd.org/index.php/pipd/article/view/46_2_1_GENETIC_SURVEY_OF_INVASIVE_S._PNEUMONIAE_SEROTYPES_IN_BUL.