Hurtado, D. J., and J. B. Abraham. “The Clinical Safety and Efficacy of Upper Pole Access Percutaneous Nephrolithotomy (uPPCNL) for Inferior Pole Stones”. Philippine Journal of Urology, vol. 27, no. 1, Feb. 2020, pp. 1-5, https://pjuonline.com/index.php/pju/article/view/34.