Velikov, P., and T. Valkov. “Clinical and Mutagenic Spectrum of Highly Pathogenic Avian Influenza A(H5N1) Clade 2.3.4.4B: A Narrative Review”. Acta Medica Bulgarica, vol. 53, no. 3, Sept. 2026, pp. 75-82, https://doi.org/10.2478/AMB-2026-0076.