Grimoire Encyclopædia

The demon Astaroth appears in the grimoires Munich Manual of Demonic Magic, The Cambridge Book of Magic, Hygromanteia, The Magus, The Discoverie of Witchcraft, The Book of the Office of Spirits, Three Books of Occult Philosophy, The Grimoire of Pope Honorius, Grimorium Verum, The Book of Abramelin, The Book of Oberon, Pseudomonarchia Daemonum, The Lesser Key of Solomon, and Dictionnaire Infernal

From The Lesser Key of Solomon, Crowley/Mathers edition:

Astaroth

The Twenty-ninth Spirit is Astaroth. He is a Mighty, Strong Duke, and appeareth in the form of an hurtful Angel riding on an Infernal Beast like a Dragon, and carrying in his right hand a Viper. Thou must in no wise let him approach too near unto thee, lest he do thee damage by his Noisome Breath. Wherefore the Magician must hold the Magical Ring near his face, and that will defend him. He giveth true answers of things Past, Present, and to Come, and can discover all Secrets. He will declare wittingly how the Spirits fell, if desired, and the reason of his own fall. He can make men wonderfully knowing in all Liberal Sciences. He ruleth 40 Legions of Spirits. His Seal is this, which wear thou as a Lamen before thee, or else he will not appear nor yet obey thee, etc.