Stuttgart, Württembergische  Landesbibliothek jur. 71, fol. 8v

134 of Justinian's 168 Novellae  were arranged into the medieval Authenticum.

Authenticae were added to the margins of Codex and the Institutes to  create new norms for twelfth-century society

Opinio communis:  Simply updating the Codex with Justinian's Novellae

Hermann Lange,  Römisches Recht im Mittelalter, 1: Die Glossatoren (München: C.H. Beck’sche Verlagsbuchhandlung, 1997) 74-85

Piero Fiorelli, Iuliani Epitome latina Novellarum Iustiniani secondo l’edizione di Gustavo Hänel e col glossario d’Antonio Agustín (Legum Iustiniani imperatoris vocabularium. Firenze: Universit degli Studi di Firenze, Dipartimento di Teoria e Storia del Diritto, 1996).

*Giovanni Baptista Palmieri (Johanne Baptista Palmerio) Authenticarum collectio antiqua in Scripta anectoda glossatorum vel glossatorum aetate composita (Bibliotheca iuridica medii aevi 3; Bologna 1901) 68-95