trum, Amsterdam, 1971.

<p></p><dt><a name="kamada89">57</a>
<dd>T. Kamada and S. Kawai<br>
<em>An algorithm for drawing general undirected graphs.</em><br>
Information Processing Letters, 31, pp. 7-15, 1989.

<p></p><dt><a name="fruchterman91">58</a>
<dd>T. Fruchterman and E. Reingold<br>
  <em>Graph drawing by force-directed placement.</em><br>
Software--Practice &amp; Experience, 21 (11), pp. 1129-1164, 1991.

<p></p><dt><a name="coleman83">59</a>
<dd>Thomas F. Coleman and Jorge J. More<br>
  <em>Estimat