Pavlova, Dyana, Ivelina Trifonova, Neli Korsun, Petar Velikov, Ivan Ivanov, Daniel Ivanov, Trifon Valkov, and Iva Christova. “ETIOLOGY, CLINICAL MANIFESTATIONS, AND AGE CHARACTERISTICS OF MIXED VIRAL RESPIRATORY INFECTIONS WITHIN 2024-2025”. PROBLEMS of Infectious and Parasitic Diseases 54, no. 1 (May 11, 2026): 5–15. Accessed May 14, 2026. https://pipd.ncipd.org/index.php/pipd/article/view/54-1-1-etiology-clinical-manifestations-and-age-characteristics.