Masdor, N. A., M. Halmi, B. Gunasekaran, and M. Sulaiman. “Screening of Heavy Metals in Selected Vegetables Using the Papain Inhibitive Assay”. Asian Journal of Plant Biology, vol. 2, no. 2, Dec. 2014, pp. 66-69, doi:10.54987/ajpb.v2i2.184.