S. G. Angelova, I. L. Georgieva, A. A. Teodosieva, and N. S. Korsun, “Neuraminidase Inhibitor Susceptibility of Influenza Viruses Circulating in Bulgaria during the Last Four Consecutive Epidemic Seasons (2011/12 to 2014/15)”, ASRJETS-Journal, vol. 12, no. 1, pp. 162–169, May 2015.