Muhammad Sohail, Muhammad Akram Malik, and Muhammad Khalid et al. “PERCUTANEOUS NEPHROLITHOTOMY THROUGH UPPER CALYCEAL APPROACH FOR COMPLEX LOWER POLAR RENAL CALCULI ”. Journal of University Medical & Dental College, Vol. 6, no. 3, Sept. 2015, pp. 26-31, http://jumdc.com/index.php/jumdc/article/view/241.