Naive Lie Theory
《Naive Lie Theory》 · 印刷第 21 页 Chapter 2 章首域的约定、第 108 页 Section 6.4「Maximal tori, further properties of Borel groups」节首对象约定及极大环面定义（省略中间内容）
$k$ is an algebraically closed field and $F$ a subfield. All algebraic varieties are over $k$. […] In this section $G$ is a connected linear algebraic group. A maximal torus of $G$ is a subtorus of $G$ that is not strictly contained in another subtorus.