Dike, D. N., C. C. Ibe, E. A. Ejem, O. Erumaka, and O. E. Chukwu. “Estimation of Inter-City Travel Demand for Public Road Transport in Nigeria”. Journal of Sustainable Development of Transport and Logistics, vol. 3, no. 3, Dec. 2018, pp. 88-98, doi:10.14254/jsdtl.2018.3-3.7.