More on rings: https://en.wikipedia.org/wiki/Ring_(m....

The detailed proof of Fermat’s Last Theorem for regular primes can be found in a very well-written article by Keith Conrad: https://kconrad.math.uconn.edu/blurbs....

...And another good source: http://www.math.columbia.edu/~ila/Kum....

The original approach by Lamé (which outlines an overall erroneous proof but nevertheless provides the valuable decomposition of the left side of the Fermat’s equation; in French): https://gallica.bnf.fr/ark:/12148/bpt....

...And English commentary to the article above: https://math.stackexchange.com/questi....

An interesting thread on (non-)unique factorization in cyclotomic rings of integers: https://math.stackexchange.com/questi....

Overview of progression on Fermat’s Last Theorem over time: https://en.wikipedia.org/wiki/Fermat'....

More on regular and irregular primes: https://en.wikipedia.org/wiki/Regular....

The Fundamental Theorem of Algebra: https://en.wikipedia.org/wiki/Fundame....