Hart, H. L. A., Bulloch, P. A., & Raz, J. (2012). The concept of law (3rd ed.). Oxford University Press.

Hart, H. L. A., Penelope A. Bulloch, and Joseph Raz. The Concept of Law. 3rd ed. Oxford: Oxford University Press, 2012.

Hart, H. L. A., et al. The Concept of Law. 3rd ed. Oxford University Press, 2012.