Ogunrinde, R. B., and T. E. Olaosebikan. 2016. “Combination of Penalty Function, Lagrange Multiplier and Conjugate Gradient Methods for the Solution of Constrained Optimization Problems”. Asian Bulletin of Energy Economics and Technology 3 (1):1-8. https://doi.org/10.20448/journal.507/2016.3.1/507.1.1.8.