The demon Valefar appears in the grimoires Book of Incantations, The Discoverie of Witchcraft, The Grand Grimoire, Pseudomonarchia Daemonum, and The Lesser Key of Solomon
From The Lesser Key of Solomon, Crowley/Mathers edition:
The Sixth Spirit is Valefor. He is a mighty Duke, and appeareth in the shape of a Lion with an Ass's head, bellowing. He is a good Familiar, but tempteth them he is a familiar of to steal. He governeth 1o Legions of Spirits. His Seal is this, which is to be worn, whether thou wilt have him for a Familiar, or not.
Timeline of related events
1536Publication of De praestigiis daemonum (lists this demon)
1584Publication of The Discoverie of Witchcraft (lists this demon)
1641Publication of the Lesser Key of Solomon (lists this demon)