D. Paul, A. Rahman, M. Ilias, and M. M. Hoq, “Production and Characterization of Keratinolytic Protease of <i>Bacillus licheniformis</i> MZK-03 Grown on Feather Mill”, Bangla. J. Microbiol., vol. 24, no. 1, pp. 57–61, Oct. 2008.