Roy, Flechner; Bouget, Helene; Coumert, Magali. Pope Gregory and the British: Mission as a Canonical Problem. Histoires des Bretagnes. French: CRBC. 2015-12-7: 47–65 [2022-11-02]. ISBN 979-1092331219. (原始内容存档于2022-11-02).请检查|date=中的日期值 (帮助) 引文格式1维护:日期与年 (link)
Roy, Flechner; Bouget, Helene; Coumert, Magali. Pope Gregory and the British: Mission as a Canonical Problem. Histoires des Bretagnes. French: CRBC. 2015-12-7: 47–65 [2022-11-02]. ISBN 979-1092331219. (原始内容存档于2022-11-02).请检查|date=中的日期值 (帮助) 引文格式1维护:日期与年 (link)