Ngumah, Chima, Jude N. Ogbulie, Justina C. Orji, and Ekpewerechi S. Amadi. 2013. “BIOGAS POTENTIAL OF ORGANIC WASTE IN NIGERIA”. Journal of Urban and Environmental Engineering 7 (1):110-16. https://doi.org/10.4090/juee.2013.v7n1.110-116.