Babajide, S. O., O. K. Oderinde, A. K. Akinlabi, and A. O. Egbemuyiwa. “Exhaust Hydrocarbon Emission Concentration Level in Abeokuta Metropolis, Ogun State, Nigeria: A Case Study of Commercial Motorcycles (Okada)”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 23, no. 1, June 2015, pp. 167-80, https://gssrr.org/index.php/JournalOfBasicAndApplied/article/view/4036.