title: How to group and reference with lookahead
body: <p>In this example:</p>
  
  <pre><code>("Talking with Bengt Holmstrom 1" "#44")
  ("Chapter 1 What is Economics? 3" "#46")
  </code></pre>
  
  <p>, which is matched by regex <code>^(?!.*(Chapter|Part)).*\n\("Chapter.*\n</code>, I would like to 
  have two groups <code>("Talking with Bengt Holmstrom 1" "#44")</code> and <code>("Chapter 1 What is Economics? 3" "#46")</code>.</p>
  
  <p>To group, the above regex is modified to be<code>^((?!.*(Chapter|Part)).*)\n(\("Chapter.*)\n</code>. I want to refer to the two groups, but using <code>\1</code> and <code>\2</code> as their references as in <code>\1\2</code> doesn't work. I was wondering if anything is wrong?</p>
  
  <p>BTW, I am using gedit regex plugin.</p>
  
  <p>Thanks!</p>