Wade, R. C., Winn, P. J., Schlichting, I., & Sudarko, S. (2004). A survey of active site access channels in cytochromes P450. Journal of Inorganic Biochemistry, 98(7): 1, pp. 1175-1182. Retrieved from http://dx.doi.org/10.1016/j.jinorgbio.2004.02.007.