A Course in Finite Group Representation Theory
《A Course in Finite Group Representation Theory》 · 第 285 页 · Section 7.1「Transcendence Bases」，Definition 2
Let $L/K$ be a field extension and $X$ an algebraically independent system of elements in $L$. Then $X$ is called a transcendence basis of $L/K$ if $L$ is algebraic over $K(X)$.