Reference for a particular case of the classification theorem of covering spaces

Question

Let $X$ be a connected topological space (maybe some other hypothesis should be imposed on $X$). Then I'd like a reference for the following result:

The sets: $$A=\{\text{equivalence classes of degree $d$ connected topological coverings of $X$}\}$$ $$B=\{\text{conjugacy classes of subgroups $H\subseteq \pi_1(X)$ of index $d$}\}$$ are in bijective correspondence.

Many thanks.

Answer 1

Hatcher's algebraic topology book http://www.math.cornell.edu/~hatcher/AT/ATpage.html

Page 67 (theorem 1.38)