List of Parent-Child Terms

foreach (get_terms('sources', array('hide_empty' => false, 'parent' => 0)) as $parent_term) {
        echo "
<div class='col-sm-6'>";
        $URL = z_taxonomy_image_url($parent_term->term_id);
        echo "<img src='$URL'>";
        echo '</div>

';
        echo "
<div class='col-sm-6'>
";
        echo '
<h1>' . $parent_term->name . '</h1>

';
        foreach (get_terms('sources', array('hide_empty' => false, 'parent' => $parent_term->term_id)) as $child_term) {
            $link = get_term_link($child_term->name, 'sources');
            echo "

<a href='$link'>" . $child_term->name . "</a>

";
        }
        echo '</div>

';
    }