In this country the Permian question has long troubled our geologists. For more than forty years it has been discussed, and up to the present time little advancement appears to have been made. Recently, interest has been awakened in the subject, and many workers have begun to attack the problems anew.
Proceedings of the Iowa Academy of Sciences
©1898 Iowa Academy of Science, Inc.
Keyes, Charles R.
"Permian Rocks of Eastern Russia,"
Proceedings of the Iowa Academy of Science, 6(1), 229-231.
Available at: https://scholarworks.uni.edu/pias/vol6/iss1/30