Khan, A. R., and F. Siddiqui. “Regional Prevalence of Different Types of Sinusitis at a Tertiary Care Centre in Northern India”. International Journal of Otorhinolaryngology and Head and Neck Surgery, vol. 6, no. 5, Apr. 2020, pp. 969-73, doi:10.18203/issn.2454-5929.ijohns20201697.