I. Alexiev, “MOLECULAR EPIDEMIOLOGICAL ANALYSIS OF THE TRANSMISSION CLUSTERS OF THE HIV-1 CIRCULATING RECOMBINANT FORMS CRF01_AE AND CRF02_ AG IN BULGARIA”, Probl Infect Parasit Dis, vol. 48, no. 1, pp. 25–32, May 2020, doi: 10.58395/pipd.v48i1.30.