“Short Communication Optimization of Substrate Concentration for Enhanced Citric Acid Production by Aspergillus niger M-101: Short Communication: Citric Acid Production by A. niger”, Pakistan Journal of Scientific & Industrial Research, vol. 52, no. 5, pp. 275–277, Oct. 2009, Accessed: Mar. 10, 2026. [Online]. Available: https://www.v2.pjsir.org/index.php/biological-sciences/article/view/564