Remark 4.2.3.10. Let $f: X \rightarrow S$ be a morphism of simplicial sets. Then $f$ is a covering map (in the sense of Definition 3.1.4.1) if and only if $f$ is both a left covering map and a right covering map (in the sense of Definition 4.2.3.8).
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$