1. Apollonov, M. K, Bandaletov, S. M. & Nikitin, I. F. 1980.The Ordovician-Silurian boundary in Kazakhstan. Nauka, Alma-Ata, 300 pp. [in Russian].
2. Bancroft, B. B. 1949.Welsh Valentian brachiopods and the Strophomena antiquata Group of fossil brachiopods. Privately published, Mexborough, 16 pp. 3 pls.
3. Barrande, J. 1879.Système Silurien du Centre de la Boheme, Ière Partie, Recherches Paléontologiques, vol. 6. Classe des Mollusques: Ordre des Brachiopodes. Published by the author, Paris, 226 pp. 153 pls.
4. Barskov, I. S. 1972.Late Ordovician and Silurian cephalopod molluscs of Kazakhstan and Central Asia. Nauka, Moscow, 112 pp. [in Russian].