K. Mokgohloa, G. Kanakana-Katumba, R. Maladzhi, and S. Xaba "A Grounded Theory Approach to Digital Transformation in the Postal Sector in Southern Africa", Advances in Science, Technology and Engineering Systems Journal, vol. 6, no. 2, pp. 313–323, 2021, doi: 10.25046/aj060236.