The Clavis Melitonis is an early medieval Biblical glossary, which I'm editing for Corpus Christianorum.
I'll be assembling some materials towards this edition here.
Here's a bibliography, for a start:
Berger, Samuel, Histoire de la Vulgate pendant les premiers siècles du Moyen Âge (Paris: Hachette, 1893).
Contreni, John J., 'Carolingian Biblical Culture', in Iohannes Scottus Eriugena: The Bible and Hermeneutics, Proceedings of the Ninth International Colloquium of the Society for the Promotion of Eriugenian Studies held at Leuven and Louvain-la-Neuve June 7-10, 1995, ed. Gerd Van Riel, Carlos Steel, and James McEvoy (Leuven: Leuven University Press, 1996), pp. 1-23.
Contreni, John J., 'Carolingian Biblical Studies', in Carolingian Essays: Andrew W. Mellon Lectures in Early Christian Studies, ed. Uta-Renate Blumenthal (Washington, DC: Catholic University of America Press, 1983), pp. 71-98.
Contreni, John J., 'Learning in the Early Middle Ages', in Carolingian Learning, Masters and Manuscripts (Aldershot: Ashgate, 1992), pp. 1-21.
Dahlhaus-Berg, Elisabeth, Nova antiquitas et antiqua novitas: typologische Exegese und isidorianisches Geschichtbild bei Théodulf von Orleans (Köln: Bohlau, 1975).
Delisle, Léopold, 'Les Bibles de Théodulfe', Bibliothèque de l'École des Chartes, 40 (1879), 5-47.
Freeman, Ann, 'Theodulf of Orleans: a Visigoth at Charlemagne's Court', in L'Europe héritière de l'Espagne wisigothique, ed. Jacques Fontaine & Christine Pellistrandi (Madrid: Rencontres de la Casa de Velázquez, 1992), pp. 185-94.
Freeman, Ann, 'Theodulf of Orléans and the Psalm Citations of the "Libri Carolini"', Revue bénédictine, 97 (1987), 195-224.
Ganz, David, 'Mass Production of Early Medieval Manuscripts: the Carolingian Bibles from Tours', in The Early Medieval Bible: its Production, Decoration and Use, ed. Richard Gameson (Cambridge: Cambridge University Press, 1994), pp. 53-62.
Gorman, Michael, 'Theodulf of Orléans and the Exegetical Miscellany in Paris Lat. 15679', Revue bénédictine, 109 (1999), 278-323.
Gorman, Michael, 'The Visigothic Commentary on Genesis in Autun 27 (S.29)', Recherches augustiniennes, 30 (1997), 167-269.
Heyse, Elisabeth, Hrabanus Maurus' Enzyklopädie 'De rerum naturis': Untersuchungen zu den Quellen und zur Methode der Kompilation (Munich, 1969).
Kaczynski, Bernice M., 'Edition, Translation, and Exegesis: the Carolingians and the Bible', in 'The Gentle Voices of Teachers': Aspects of Learning in the Carolingian Age, ed. Richard E. Sullivan (Columbus: Ohio State University Press, 1995), pp. 171-85.
Laurant, Jean-Pierre, Symbolisme et écriture: le cardinal Pitra et la "Clef" de Méliton de Sardes (Paris: Éditions du Cerf, 1988).
Le Maître, Philippe, 'Les Méthodes exégétiques de Raban Maur', in Haut Moyen-Âge: Culture, éducation et société, études offertes à Pierre Riché, ed. Calude Lepelley and Michael Sot (Nanterre: Editions Publidix, 1990), pp. 343-52.
McKitterick, Rosamond, 'Carolingian Biblical Production: the Tours Anomaly', in The Early Medieval Bible: its Production, Decoration and Use, ed. Richard Gameson (Cambridge: Cambridge University Press, 1994), pp. 63-77.
Mosey, David, 'Allegorical Interpretation in the West from 800 AD to 1200 AD' (unpublished doctoral dissertation, University of Toronto, 1985).
Ribémont, B., Les origines des encyclopédies médiévales: d'Isidore de Séville aux Carolingiens (Paris, 2001).
Rissel, M., Rezeption Antiker und Patristischer Wissenschaft bei Hrabanus Maurus (Bern, 1976).
Rottmanner, Odilo, 'Ein letzes Wort über die Clavis Melitonis', Theologische Quartalschrift, 78 (1896), 614-29.
Schipper, William, 'Rabanus Maurus and his sources" in: Schooling and Society: the Ordering and Reordering of Knowledge in the Western Middle Ages, ed. Alasdair A. MacDonald and Michael W. Twomey (Leuven: Peeters, 2004), pp. 1-21.
Stansbury, Mark, 'Early Medieval Biblical Commentaries, their Writers and Readers', Frühmittelalterliche Studien, 32 (1999), 49-92.
Szerwiniack, Olivier, 'Des Recueils d'interprétations de noms hébreux chez les Irlandais et le Wisigoth Théodulf', Scriptorium, 48 (1994), 187-258.
Vaciago, P., 'Towards a Corpus of Carolingian Biblical Glossaries: a Research in Progress Report', in Les Manuscrits des lexiques et glossaires de l'antiquité tardive à la fin du Moyen Âge, ed. Jacqueline Hamesse, Textes et études de Moyen Âge, 4 (Louvain-la-Neuve: Fédération Internationale des Instituts d'Études Médiévales, 1996), pp. 127-44.