Hyder, Raza Rahim, et al. “THE USEFULNESS OF INTER-RENAL RESISTIVE INDEX DIFFERENCE IN DIAGNOSING ACUTE UNILATERAL URETERIC OBSTRUCTION DUE TO CALCULUS”. Pakistan Armed Forces Medical Journal, vol. 59, no. 2, Aug. 2018, pp. 211-6, https://pafmj.org/PAFMJ/article/view/1894.