Transitional beds of the Ordovician and Silurian of the Altai Sayan province and Tyan-Shan. Tabulata and Heliolitoidea. Rossiiskaya Akademiya Nauk Sibirskoe Otdelenie Trudy Instituta Geologii i Geofiziki, 397 1978: 58-64. 63 [Zoological Record Volume 115]