Mughal, Sikander Adil, et al. “A STUDY OF EXERCISE-INDUCED BRONCHOSPASM IN URBAN AND RURAL SCHOOL CHILDREN OF SINDH”. Pakistan Journal of Physiology, vol. 4, no. 2, Dec. 2008, pp. 33-35, https://pjp.pps.org.pk/index.php/PJP/article/view/823.