Sources : Demma
Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Quadrupeds 4.29): Dempma is a beast of the size of a deer, very strong, and uses its horns on the beasts that oppose it. It is swift in running, clever in scent, and well-provided with life. The horns, as Pliny says, are sharp, rough, long beyond a cubit, and raised upwards like the palm of a man. - [Badke translation/paraphrase]