S. C. SWAIN, et al. “EFFECT OF COAL ASH ON PHYSIO-MORPHOLOGICAL AND BIOCHEMICAL CHARACTERS OF OKRA (ABELMOSCHUS ESCULENTUS L. MOENCH)”. The Bioscan, vol. 9, no. 2, Mar. 2014, pp. 653-8, https://thebioscan.com/index.php/pub/article/view/720.