php write " ' corectly

I have a little bit more complicated row than I can handle. I am echoing and I got lost in the " ', could someone help me out and tell me how to have this line correctly? Thanks!

echo '<td style="text-align: center"><a onclick=" window.open('/edit.php?id=' . $row['id'] . ','_self')"><img height="30" width="30" src="/wp-content/themes/sparkling/edit.png"/></a></td>';