<?php
 
$html = '<a href="https://w...content-available-to-author-only...e.com/user.asp?ref=fvFCF9D8N4Ak">';
 
$dom = new DOMDocument;
@$dom->loadHTML($html);
 
foreach ($dom->getElementsByTagName('a') as $tag) {
 
	$href = $tag->getAttribute('href');
 
	if (!empty($href)) {
 
		echo $queryString = parse_url($href, PHP_URL_QUERY);
	}
}