title: How can I highlight `\cite` (linebreak preserving) in latex
body: <p>How can I highlight (set a background color) <code>\cite</code> (linebreak preserving) like this:<code>[1]</code></p>
  
  <p>I got a compile error when I tried <code>\hl</code> in the package <code>soul</code> like:</p>
  
  <pre><code>\hl{\cite{xxx}}
  </code></pre>
  
  <p><code>\mobx</code> can fix this but doesn't support line break.</p>
  
  <p>I also tried <code>\colorbox</code> and <code>\newcommand\hl{\bgroup\markoverwith {\textcolor{GhostWhite}{\rule[-.5ex]{2pt}{2.5ex}}}\ULon}</code>, but they do not support line break either.</p>
  
  <h3>Compile error example</h3>
  
  <p>main.tex:</p>
  
  <pre><code>\documentclass{article}
  \usepackage{soul}
  \begin{document}
  
  \hl{{\cite{c1, c2, c3}}}
  
  \bibliographystyle{plain}
  \bibliography{ref} 
  \end{document}
  </code></pre>
  
  <p>ref.bib:</p>
  
  <pre><code>@book{c1,
  ...
  }
  @book{c2,
  ...
  }
  @book{c3,
  ...
  }
  </code></pre>
  
  <h3>My QUESTION</h3>
  
  <ul>
  <li>What is the right way to highlight <code>\cite</code></li>
  </ul>