This article provides definitions and examples upon an integral element of unital commutative rings.
Watase Yasushige 2016, 'Algebraic Numbers', Formalized Mathematicshttp://www.degruyter.com/view/j/forma.2016.24.issue-4/forma-2016-0025/forma-2016-0025.xml?format=INT. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
The commutative rings with exactly two proper (unital) subrings are characterized.
David E. Dobbs 2016, 'On the Commutative Rings with At Most Two Proper Subrings', International Journal of Mathematics and Mathematical Scienceshttp://dx.doi.org/10.1155/2016/6912360. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)