ご参考
１）
大阿久先生のPDF
https://www.lab.twcu.ac.jp/oaku/index_jp.html
大阿久俊則
講義録（学部）
11 ガロア理論入門, 「ガロア理論入門」演習問題解答,
https://www.lab.twcu.ac.jp/oaku/galois.pdf
ガロア理論入門（体と群と方程式）
東京女子大学
PDF
ガロア理論入門（大阿久俊則）. 20. 6 ガロア拡大とガロア群. 定義 6.1 C ⊃ L ⊃ K を体の拡大とする．このとき L ⊃ K がガロア拡大(Galois extension). または正規拡大 ...
49 ページ

２）英語読める人に お薦め Brent Everitt （分かり易い）
[Submitted on 12 Apr 2018]
Galois Theory - a first course
Brent Everitt
These notes are a self-contained introduction to Galois theory, designed for the student who has done a first course in abstract algebra.

３）５次方程式の幾何 趣味の世界ですが
https://people.reed.edu/~jerry/Quintic/quintic.html
https://people.reed.edu/~jerry/Quintic/quintic.pdf
Geometry of the Quintic
The book as pdf
(Copyright 2009 by Jerry Shurman. Any part of the material protected by this copyright notice may be reproduced in any form for any purpose without the permission of the copyright owner, but only the reasonable costs of reproduction may be charged. Reproduction for profit is prohibited.)
Wiley has returned the copyright of the book to me, and the book is posted here as pdf for anyone who wants it. The typesetting isn't all that it should be, and there is at least one nontrivial error in the book, but I am leaving things as they are.
https://people.reed.edu/~jerry/index.html
Jerry Shurman
Professor
Reed College
Department of Mathematics and Statistics

４）これも ５次方程式の趣味の世界
https://www.ams.org/journals/notices/202404/noti2923/noti2923.html
https://www.ams.org/journals/notices/202404/rnoti-p444.pdf
The Quintic, the Icosahedron, and Elliptic Curves
Bruce Bartlett APRIL2024 NOTICES OF THE AMERICAN MATHEMATICAL SOCIETY VOLUME 71, NUMBER 4

まあ、こんな感じね（＾＾