The demon Stolas appears in the grimoires The Discoverie of Witchcraft, The Book of Spirits, Pseudomonarchia Daemonum, The Lesser Key of Solomon, and Dictionnaire Infernal
From The Lesser Key of Solomon, Crowley/Mathers edition:
The Thirty-sixth Spirit is Stolas, or Stolas. He is a Great and Powerful Prince, appearing in the Shape of a Mighty Raven at first before the Exorcist; but after he taketh the image of a Man. He teacheth the Art of Astronomy, and the Virtues of Herbs and Precious Stones. He governeth 26 Legions of Spirits; and his Seal is this, which is, etc.