The Scholastic Analysis of Usury. Cambridge, Massachusetts: Harvard University Press, 1957.

Contraception: A History of its Treatment by the Catholic Theologians and Canonists. Cambridge, Massachusetts: The Belknap Press of Harvard University Press, 1966.

Power to Dissolve:  Lawyers and Marriages in the Courts of the Roman Curia.  Cambridge, Massachusetts: The Belknap Press of Harvard University Press, 1972.

Bribes. New York-London: Macmillan Publishing Company, 1984.