Predvaritelʹnoe opisanie novykh form permskoĭ i triasovoĭ fauny nazemnykh pozvonochnykh SSSR = Preliminary description of the new Permian and Triassic tetrapoda from USSR - Efremov, Ivan Antonovich, 1907-1972 (Trudy Paleontologicheskogo instituta, 1940)