Murchison, R.I.; de Verneuil, E.; von Keyserling, A. (1845). Geology of Russia in Europe and the Ural Mountains. Vol. 1: Geology. London: John Murray. s. 138–139. «...Convincing ourselves in the field, that these strata were so distinguished as to constitute a system, connected with the carboniferous rocks on the one hand, and independent of the Trias on the other, we ventured to designate them by a geographical term, derived from the ancient kingdom of Permia, within and around whose precincts the necessary evidences had been obtained. ... For these reasons, then, we were led to abandon both the German and British nomenclature, and to prefer a geographical name, taken from the region in which the beds are loaded with fossils of an independent and intermediary character; and where the order of superposition is clear, the lower strata of the group being seen to rest upon the Carboniferous rocks.»
