 Mathematics Magazine, <br>
          Volume 74, Number 1, February 2001, pages 26-32.
        </li>
        <li>
          J Simoes Pereira,<br>
          Algorithm 234: Poisson-Charliers Polynomials,<br>
          Communications of the ACM,<br>
          Volume 7, Number 7, July 1964, page 420.
        </li>
        <li>
          Charles Pinter,<br>
          A Book of Abstract Algebra,<br>
          Second Edition,<br>
          McGraw Hill, 2003,<br>
          ISBN: 0072943505,<br>
          LC: QA162.