Derry, George H (1913). "St. Bruno (2)" . In Herbermann, Charles (ed.). Catholic Encyclopedia. New York: Robert Appleton Company. "St. Bruno[...] had never been formally canonized. His cult, authorized for the Carthusian Order by Leo X in 1514, was extended to the whole church by Gregory XV, 17 February 1623, as a semi-double feast, and elevated to the class of doubles by Clement X, 14 March 1674."
