Twelfth-century decretal collections and their importance in English history / by Charles Duggan. - University of London, 1963.

Decretals and the creation of "new law" in the twelfth century / Charles Duggan. - Aldershot (England), [etc.], 1998.

Decretales ineditae saeculi XII / edited and revised by Stanley Chodorow and Charles Duggan. - Città del Vaticano, 1982. ed.

Papers read at the first Winter and summer meetings of the ecclesiastical history Society / edited by C. W. Dugmore and Charles Duggan. - London, c1964. ed.