regex.syntax.basic_extended.references">References</a>
      </h4>
<p>
        <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/xbd_chap09.html" target="_top">IEEE
        Std 1003.1-2001, Portable Operating System Interface (POSIX ), Base Definitions
        and Headers, Section 9, Regular Expressions.</a>
      </p>
<p>
        <a href="http://www.opengroup.org/onlinepubs/000095399/utilities/grep.html" target="_top">IEEE
        Std 1003.1-2001, Portable Operating System Interface (POSIX ),