The sources of the Ben. Ed. of the Letters were Coislinianus 237, XIth c., a Codex Harlæanus of the Xth or XIth c., and a Codex Medicæus, Codex Regius 2293, Codex Regius 2897, Codex Regius 2896, Codex Regius 2502, Codex Regius 1824, Codex Regius 1906, and Codex Regius 1908.