P. D. Kale, A. B. Bodade, and G. N. Chaudhari, “STUDY OF IMMOBILIZATION OF UREASE ON PVA-NANO NiFe2O4 NANOCOMPOSITE FOR BIOSENSOR APPLICATIONS”, Int J Pharm Pharm Sci, vol. 8, no. 7, pp. 380–385, Jul. 2016.