Stukalina 1965. [Sea lilies of the Karaespinsk stratum]. Stratigraphy of Lower Palaeozoic and Silurian deposits of central Kazakhstan], Stratigraphy of Lower Palaeozoic and Silurian deposits of central Kazakhstan] Gosud. Geol. Komitet SSSR. Tsentral.-Kazakh. Geol. Upravlenie. Izd. 'Nedra': Leningrad. [In Russian]", 1965: 134-145. Chapter pagination: 134-145