Kaidar, E. K., A. K. Turgambayeva, B. S. Zhussupov, B. S. Serik, and M. K. Zhanaliyeva. “Secondary Attack Rate of the COVID-19: General Characteristics of Confirmed and Probable Cases”. International Journal of Health Sciences, vol. 6, no. 3, Sept. 2022, pp. 1468-82, doi:10.53730/ijhs.v6n3.13082.