References
- Bogoslovskaya , M. F. 1988 . “ About the upper boundary of the Lower Permian, according to the ammonoids ” . In The Permian System: Some Problems of the Stratigraphy and Development of the Biota , 16 – 26 . Kazan' : University of Kazan' .
- Chuvashov , B. I. , Leven , E. Ya. Davydov , V. I. 1986 . Carboniferous and Permian Boundary Deposits of the Urals and Pre-Urals Region and Central Asia , Moscow : Nauka Press .
- Leonova , T. B. Dmitriyev , V. J. 1989 . Early Permian Ammonoids of the Southeast Pamir , Moscow : Nauka Press .
- Leven , E. Ya. 1974 . Divisions of the Permian system . Bull. Mosk. Obshch. Isp. Prirody, otd. Geol. , : 47 – 64 .
- Leven , E. Ya. 1975 . The stage scale of the Tethys Permian deposits . Bull. Mosk. Obshch. Isp. Prirody, otd. Geol. , 50 ( 1 ) : 5 – 21 .
- Leven , E. Ya. 1980 . Explanatory Note to the Stratigraphic Scale of the Tethys Permian Deposits , Leningrad : VSEGEI .
- Zakharov , Y. D. 1986 . Type and hypotype of the Permian-Triassic boundary . Memoirs of the Italian Geological Society , 34 : 217 – 289 .