References
- Garwood , E. J. 1910 . Geology of Northumberland and Durham . Geology in the Field , : 681 – 681 .
- North , F. J. 1920 . On Syringothyris, Winchell, and certain Carboniferous Brachiopoda referred to Spiriferina, d'Orbigny . Quart. Journ. Geol. Soc. , lxxvi : 212 – 212 .
- Smith , S. 1910 . The Faunal Succession of the Upper Bernician . Trans. Nat. Hist. Soc. Northumberland, Newcastle-on-Tyne, n.s. , iii : 596 – 596 . 598, 627.
- Thomas , I. 1914 . The British Carboniferous Producti. I. Genera Pustula and Overtonia . Mem. Geol. Surv. Gt. Britain, Palæontology , i : 4 – 4 .
- Trottrr , F. M. 1926 . Summary of Progress for 1925 , : 82 – 82 .
- Tschernyschew , T. 1902 . Die obercarbonischen Brachiopoden des Ural und des Timan . Mém. Com. Géol. Petrograd , xvi ( 2 ) : 620 – 620 .
- Tschernyschew , T. 1914 . Die Fauna der oberpaläozoischen Ablagerungen des Darvas . Mém. Com. Géol. Petrograd , civ : 62 – 62 .