Gupta, P. C., J. P. Jain, and V. P. Gupta. “Gamma-Ray Dose Rate at an External Point from a Spherical Radioactive Source”. Defence Science Journal 12, no. 4 (April 30, 2014): 357–362. Accessed August 18, 2025. https://publications.drdo.gov.in/ojs/index.php/dsj/article/view/7006.