Ibrahim, T. H., E. Betiku, B. O. Solomon, J. O. Oyedele, G. O. Olaifa, and A. A. Adekunle. “Validation of Wet Chemistry Method As Alternative to Gas Chromatography for Biogas Methane Content Determination”. ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT, Vol. 19, no. 1, Mar. 2023, pp. 23-32, https://azojete.com.ng/index.php/azojete/article/view/700.