Pencheva, Viktoria, Aleksandar Kolevski, and Snezhina Kandilarova. 2025. “Comparison of Anti-Receptor Binding Domain of SARS-CoV-2 Spike Protein Humoral Response Between Infected, Vaccinated and Vaccinated After Natural Exposure Subjects over 12-Months Follow-up Period”. Proceedings of the Bulgarian Academy of Sciences 78 (3). Sofia, Bulgaria:441–449. https://doi.org/10.7546/CRABS.2025.03.14.