He is depicted in the shape of Sagittarius, which is as a centaur with a bow and arrows.
According to other authors he teaches Medicine, and has the head of a lion and five goat legs surrounding his body to walk in every direction.
Although the etymology of his name is uncertain, curiously there was an ancient city named "Buer" (now Gelsenkirchen) in Westphalia, Germany.
See also The Lesser Key of Solomon, Ars Goetia.