1. Aksarina, N.A. and Pelman, Yu.L., Kembriiskie brakhiopody i dvustvorchatye mollyuski Sibiri (Cambrian Brachiopods and Bivalve Mollusks of Siberia), Tr. Inst. Geol. Geofiz. Sib. Otd. Akad. Nauk SSSR, vol. 362, Moscow: Nauka, 1978.
2. Bell, W.Ch., Prototreta, a new genus of brachiopod from the Middle Cambrian of Montana, Michigan Acad. Sci., Papers for 1937/1938, vol. 23, pp. 403–407.
3. Bell, W.Ch., Cambrian Brachiopoda from Montana, J. Paleontol., 1941, vol. 16, no. 3, pp. 193–255.
4. Ermak, V.V. and Pelman, Yu.L., Molluscs and brachiopods from the Cambrian of northern Kharaulakh, in Biostratigrafiya i paleontologiya kembriya Severnoi Azii (Biostratigraphy and Paleontology of the Cambrian of Northern Asia), Tr. Inst. Geol. Geofiz. Sib. Otd. Akad. Nauk SSSR, vol. 669, Moscow: Nauka, 1986, pp. 188–200.
5. Gorjansky, V.Yu. and Koneva, S.P., Lower Cambrian inarticulate brachiopods of the Malyi Karatau Range, southern Kazakhstan, in Biostratigrafiya i paleontologiya nizhnego i srednego kembriya Severnoi Azii (Biostratigraphy and Paleontology of the Lower and Middle Cambrian of Northern Asia), Tr. Inst. Geol. Geofiz. Sib. Otd. Akad. Nauk SSSR, vol. 541, Moscow: Nauka, 1983, pp. 128–138.