Akpootu, D. O., B. I. Tijjani, and U. M. Gana. “Time Series and Empirical Orthogonal Transformation Using Meteorological Parameters across the Climatic Zones in Nigeria”. International Journal of Environment and Climate Change, Vol. 9, no. 5, June 2019, pp. 257-72, doi:10.9734/ijecc/2019/v9i530113.