Book,<br>
          Fourth Edition,<br>
          Cambridge University Press, 1999,<br>
          ISBN: 0-521-64314-7,<br>
          LC: QA76.95.W65.
        </li>
        <li>
          ML Wolfson, HV Wright,<br>
          ACM Algorithm 160: Combinatorial of M Things Taken N at a Time,<br>
          Communications of the ACM,<br>
          Volume 6, Number 4, April 1963, page 161.
        </li>
        <li>
          Shanjie Zhang, Jianming Jin,<br>
          Computation of Special Functions,<br>
         