David, Moses, et al. “Virulence Factors and Beta-Lactamase Production Among Vancomycin-Resistant Enterococcus Faecalis Isolated from Clinical Samples and Hospital Environment”. International Journal of Biological Research, vol. 5, no. 1, Dec. 2016, pp. 1-5, https://doi.org/10.14419/ijbr.v5i1.6811.