Layeni, A. T., A. I. Olanrewaju, C. N. Nwaokocha, M. A. Waheed, S. O. Giwa, S. I. Kuye, and K. A. Adedeji. “Comparative Engineering Economic Analysis of a Variable Refrigerant Flow and Mini-Split Air Conditioning System Design”. ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT, Vol. 15, no. 1, Mar. 2019, pp. 55-66, https://azojete.com.ng/index.php/azojete/article/view/239.