Onyango, K. A., and G. W. . Mariga. “Comparative Analysis on the Evaluation of the Complexity of C, C++, Java, PHP and Python Programming Languages Based on Halstead Software Science”. International Journal of Computer and Information Technology(2279-0764), vol. 12, no. 1, Mar. 2023, doi:10.24203/ijcit.v12i1.294.