1. M. Bôcher. Introduction to Higher Algebra. Macmillan, New York, 1907. Republished by Dover Publications, New York, 1964. German translation as [26].
2. M. Bôcher. Einführung in die höhere Algebra. Teubner, Leipzig, 1910. Translated by H. Beck.
3. A. Cayley. A memoir on the theory of matrices. Phil. Trans. R. Soc. London, 148:17–37, 1858. Reprinted in Papers 2, 475–496.
4. A. Châtelet. Leçons sur la théorie des nombres. (Modules. Entiers algébrique. Réduction continuelle.). Gauthier–Villars, Paris, 1913.
5. L. E. Dickson. Modern Algebraic Theories. Sandborn, Chicago, 1926.