Harrald, John R., Hugh W. Stephens and Johann Rene vanDorp. "A Framework for Sustainable Port Security" Journal of Homeland Security and Emergency Management, 1.2 (2004): -. Retrieved 22 May. 2013, from doi:10.2202/1547-7355.1029

Harrald, J., Stephens, H. & vanDorp, J. (2004). A Framework for Sustainable Port Security. Journal of Homeland Security and Emergency Management, 1(2), pp. -. Retrieved 22 May. 2013, from doi:10.2202/1547-7355.1029

Harrald, John R., Hugh W. Stephens and Johann Rene vanDorp. 2004. A Framework for Sustainable Port Security. Journal of Homeland Security and Emergency Management. 1(2): -. Retrieved 22 May. 2013, from doi:10.2202/1547-7355.1029