1. Assereto, R. (1963): The Paleozoic Formations in Central Elburz (Iran) (Preliminary note). — Riv. Ital. Paleont. e Strat,69, 503–543.
2. Bengtson, St. (1970): The Lower Cambrian fossil Tommotia. — Lethaia,3, 363–392.
3. Eisenack, A. (1964): Mikrofossilien aus dem Silur Gotlands. Phosphatische Reste. — Paläont. Z.38, 170–179, Taf. 16-17.
4. Ethington, R. L. &Clark, D. L. (1965): Lower Ordovician Conodonts and other Microfossils from the Columbia Ice Fields Section, Alberta, Canada. — Brigham Young Univers. Geol. Stud.,12, 185–205.
5. Fonin, W. D. &Smirnowa, T.N. (1967): Nowaja gruppa Problematitscheskich Rannekembriiski Organismow i Neketorie metodi ich preparirowanija. — Paleont. J. Akad. NAUK, SSSR., 15-27.