The demon Gamigin appears in the grimoires Book of Incantations, The Discoverie of Witchcraft, Pseudomonarchia Daemonum, and The Lesser Key of Solomon
From The Lesser Key of Solomon, Crowley/Mathers edition:
The Fourth Spirit is Samigina, a Great Marquis. He appeareth in the form of a little Horse or Ass, and then into Human shape doth he change himself at the Request of the Master. He speaketh with a hoarse voice. He ruleth over 30 Legions of Inferiors. He teaches all Liberal Sciences, and giveth account of Dead Souls that died in sin. And his Seal is this, which is to be worn before the Magician when he is Invocator, etc.