"nofollow" class="external text" href="http://www.baconsdozen.co.uk/tools/conversion%20charts.htm">Comparison chart of BSW,BSF.BA,AF and metric equivalents</a></li>
<li><a rel="nofollow" class="external text" href="http://www.diracdelta.co.uk/science/source/b/r/british%20standard%20whitworth/source.html">BSW tapping drill for 65% and 100% and clearance drill sizes</a></li>
<li><a rel="nofollow" class="external text" href="http://www.hot.net.au/~kht/">Discusses Whitworth thread and pitch sizes and spanner si