The demon Flauros appears in the grimoires Book of Incantations, 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 Sixty-fourth Spirit is Haures, or Hauras, or Havres, or Flauros. He is a Great Duke, and appeareth at first like a Leopard, Mighty, Terrible, and Strong, but after a while, at the Command of the Exorcist, he putteth on Human Shape with Eyes Flaming and Fiery, and a most Terrible Countenance. He giveth True Answers of all things, Present, Past, and to Come. But if he be not commanded into a triangle, A, he will Lie in all these Things, and deceive and beguile the Exorcist in these things or in such and such business. He will, lastly, talk of the Creation of the World, and of Divinity, and of how he and other Spirits fell. He destroyeth and burneth up those who be the Enemies of the Exorcist should he so desire it; also he will not suffer him to be tempted by any other Spirit or otherwise. He governeth 36 Legions of Spirits, and his Seal is this, to be worn as a Lamen, etc.
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)