Afaq, Sarah, and Jawaid Iqbal. 2001. “Immobilization and Stabilization of Papain on Chelating Sepharose: A Metal Chelate Regenerable Carrier”. Electronic Journal of Biotechnology 4 (3). Valparaíso, Chile:0-0. https://preprints.pucv.cl/index.php/ejbiotechnology/article/view/v4n3-1.