Gerald, Banda, and Tailoka Frank Patson. “An Investigation on the Relationship Between the Level of Education and Monthly Income: A Case of Kitwe District of Zambia”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 49, no. 1, Dec. 2018, pp. 106-17, https://asrjetsjournal.org/American_Scientific_Journal/article/view/4406.