Khan, A. S., R. Ullah, Z. Iqbal, and S. Naz. “Frequency of Secondary Multidrug Resistance Pulmonary Tuberculosis in Category-II Failure Patients”. Pakistan Journal of Chest Medicine, vol. 23, no. 4, May 2018, pp. 139-43, https://pjcm.net/index.php/pjcm/article/view/483.