Anyanwu, V. E. and Okerentugba, P. O. (2013) “Citric Acid Production by Wild and UV – Treated Strains of Aspergillus niger on Two Different Mineral Salt Media”, International Journal of Applied Sciences and Biotechnology, 1(3), pp. 145–153. doi: 10.3126/ijasbt.v1i3.8358.