Iqba, M. Z., Q. Abbas, and M. Shafiq. “TOXIC EFFECTS OF COPPER AND ZINC ON GERMINATION AND SEEDLING GROWTH OF SOME TREES”. Biological Sciences - PJSIR, vol. 44, no. 6, Dec. 2001, pp. 351-5, https://v2.pjsir.org/index.php/biological-sciences/article/view/1972.