Textbooks of Statistics, in general, scarcely mention the topic "Common Elements" and almost no articles in periodicals are written on the subject. The following are the definitions that are given. These definitions are in terms of the correlation coefficient.
Proceedings of the Iowa Academy of Science
©1956 Iowa Academy of Science, Inc.
Brandner, Fred A.
Proceedings of the Iowa Academy of Science, 63(1), 528-533.
Available at: https://scholarworks.uni.edu/pias/vol63/iss1/53