Begum, S.A., Banu, Q. and Hoqure, B. 2013. Effect of chromium, cadmium and mercury on the gill histology of Clarias batrachus L. Chittagong University Journal of Biological Sciences. 4, 1 (Jan. 2013), 13–23. DOI:https://doi.org/10.3329/cujbs.v4i1.13383.