Foundations of the Conciliar Theory

The Contribution of the Medieval Canonists from Gratian to the Great Schism

1997

Religion, Law and the Growth of Constitutional Thought, 1150-1650

1982

The Crisis of Church & State 1050-1300

1964

The Idea of Natural Rights

Studies on Natural Rights, Natural Law and Church Law 1150-1625

1997

The Middle Ages, Volume I, Sources of Medieval History

1973

The Middle Ages, Volume II, Readings in Medieval History

1974