Hart, H. L. A. (1997). The concept of law. Oxford: Oxford University Press.
Dyfyniad Arddull ChicagoHart, H L A. The Concept of Law. Oxford: Oxford University Press, 1997.
Dyfyniad MLAHart, H L A. The Concept of Law. Oxford: Oxford University Press, 1997.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.