Goetia – S. L. MacGregor Mathers (1904) (quoted)

Naberius’ Goetic seal

 
The Twenty-fourth Spirit is Naberius. He is a most valiant Marquis, and showeth in the form of a Black Crane, fluttering about the Circle, and when he speaketh it is with a hoarse voice. He maketh men cunning in all Arts and Sciences, but especially in the Art of Rhetoric. He restoreth lost Dignities and Honours. He governeth 19 Legions of Spirits. His Seal is this, which is to be worn, etc.
Pseudomonarchia daemonum – Johann Wier (1583) (quoted)
Naberius [Naberus], alias Cerberus, is a valiant marquesse, shewing himselfe in the forme of a crowe, when he speaketh with a hoarse voice: he maketh a man amiable and cunning in all arts, and speciallie in rhetorike, he procureth the losse of prelacies and dignities: nineteene legions heare (and obeie) him.

Cerbere/Naberius – Dictionnaire Infernal

Dictionnaire Infernal – Collin de Plancy (1863) (paraphrased) 
Cerbere/ Cerberus/ Naberus is a strong and powerful demon commanding 29 legions. Wierus places him as one of the marquis of hell. Cerberus appears as a three headed dog or a raven. He has a raucous voice but presents himself as eloquent and amiable. He teaches the art of gracious living.