Ngosi, R. K., and J. Omwenga. “Factors Contributing to Non-Productive Time in Geothermal Drilling in Kenya: A Case of Menengai Geothermal Project”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 14, no. 3, Nov. 2015, pp. 16-26, https://asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/1092.