[Trilobites of the Karakol-Mikhailovsk horizon of the Lower Ordovician of the Southern Urals.] Trudy Instituta Geologii i Geokhimii Akademiya Nauk SSSR Ural'skii Nauchnyi Tsentr, No. 126 1977: 68-95. 81 [Zoological Record Volume 122]