Ali, S., I. ul-Haq, and J. Iqbal. “The Role of Mn++ Ions for High and Consistent Yield of Citric Acid in Recycling Fed-Batch Bioreactor System and Its Novelty on Kinetic Basis”. Electronic Journal of Biotechnology, vol. 5, no. 2, Aug. 2002, pp. 0-0, https://www.ejbiotechnology.info/index.php/ejbiotechnology/article/view/v5n2-3.