Naive Lie Theory
《Naive Lie Theory》 · 印刷第 21 页 Chapter 2 章首域的约定、第 101 页 Section 6.2「Parabolic subgroups and Borel subgroups」节首对象约定、第 102 页 Theorem 6.2.7 前的定义段（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 linear algebraic group over $k$. […] A Borel subgroup of $G$ is a closed, connected, solvable, subgroup of $G$, which is maximal for these properties.