Imran, M., M. Ikram, R. U. Islam, M. Anwar, H. Tariq, and M. Ahmad. “Development Operation and Characterization of Cesium Beam Atomic Clock”. The Nucleus, vol. 57, no. 2, Oct. 2020, pp. 49-55, http://thenucleuspak.org.pk/index.php/Nucleus/article/view/526.