Gregory the Great and his world - Markus, Robert Austin, 1924-2004 (Cambridge University press, 1997)
Keywords: Gregory -- I, -- Pope, -- approximately 540-604.; Church history -- Primitive and early church, ca. 30-600; 262.13 GREGORIUS I MAGNUS -- Pausschap. Heilige Stoel. Vaticaan. Paus als soeverein--GREGORIUS I MAGNUS