Php 如何访问名称中带有破折号的属性？

所以我运行了如下代码：

$quote = simplexml_load_string($xml);
$quote = $quote->Stock;
echo 'Name: ';
echo $quote->Name;
echo '<br>';
echo 'Sybmol: ';
echo $quote->Symbol;
echo '<br>';
echo 'Last Price: ';
echo $quote->Last;
echo '<br>';
echo 'Earnings To Price Ratio: ';
echo $quote->P-E;
echo '<br>';

我应该如何访问此属性/属性

$quote->{'P-E'};

$quote->{'P-E'};