Buzdar, Saeed Ahmad, et al. “COMPARISON OF PENCIL BEAM AND COLLAPSED CONE ALGORITHMS, IN RADIOTHERAPY TREATMENT PLANNING FOR 6 AND 10 MV PHOTON”. Journal of Ayub Medical College Abbottabad, vol. 22, no. 3, Sept. 2010, pp. 152-4, https://www.jamc.ayubmed.edu.pk/index.php/jamc/article/view/2890.