@book{
title = {Gregorii 1. papae Registrum epistolarum},
author = {Gregorius <<papa ; 1.>>},
editor = {Ewald, Paul},
editor = {Hartmann, Ludo Moritz},
editor = {Ripr. facs. dell'ed.: Berlin : Weidmann, 1892 },
year = {1957},
edition = {Editio secunda lucis ope expressa},
address = {Berolini },
publisher = {Weidmann},
}