“Activatory Effects of Manganese and Cobalt Ions on the Activity of Cellulase Produced by Aspergillus niger” (2013) Nigerian Journal of Biochemistry and Molecular Biology, 28(1&2), pp. 60–68. Available at: https://www.nsbmb.org.ng/journals/index.php/njbmb/article/view/315 (Accessed: 3 June 2026).