Algebraic Number Theory
《Algebraic Number Theory》 · 第 415 页 · Chapter VI，Section 8「The Reciprocity Law of the Power Residues」，Definition 8.2
For every ideal $\mathfrak b=\prod_{\mathfrak p\nmid n}\mathfrak p^{v_{\mathfrak p}}$ prime to $n$, and every number $a$ prime to $\mathfrak b$, the $n$-th power residue symbol is defined by $\left(\frac a{\mathfrak b}\right)=\prod_{\mathfrak p\nmid n}\left(\frac a{\mathfrak p}\right)^{v_{\mathfrak p}}$, with the factor equal to $1$ when $v_{\mathfrak p}=0$.