title: What is the paper "Oliver [1993]" describing a PHP algorithm to calculate text similarity?
body: <p>There is a function similar_text() in the PHP library.  The documentation (<a href="http://php.net/manual/en/function.similar-text.php" rel="noreferrer">http://php.net/manual/en/function.similar-text.php</a>) tells me that "This calculates the similarity between two strings as described in Oliver [1993]."</p>
  
  <p>Despite extensive searching, I can't find the paper that "Oliver [1993]" is referring to; nor any candidate for who "Oliver" might be.  The PHP source is undocumented.  The only other reference to Oliver 1993 is in a forum at <a href="http://www.codeguru.com/forum/showthread.php?t=41089" rel="noreferrer">http://www.codeguru.com/forum/showthread.php?t=41089</a>, and I think that information is derived from the PHP documentation.</p>
  
  <p>Anyone aware of what this might be?</p>