Muhammad Khaleel Iqbal, et al. “CORRELATION OF GLOBAL LONGITUDINAL SYSTOLIC STRAIN WITH SEVERITY OF CORONARY ARTERY DISEASE IN NON-ST-ELEVATION ACUTE CORONARY SYNDROME HAVING NORMAL EJECTION FRACTION”. Journal of Ayub Medical College Abbottabad, vol. 33, no. 3, June 2021, pp. 393-8, https://jamc.ayubmed.edu.pk/index.php/jamc/article/view/7727.