Active sources<BR><div> <a href="http://www.facebook.com/202495069911572">The Christian century, Volume 54</a><BR /> <a href="http://www.facebook.com/548542345200480">Getting Your Way: Strategic Dilemmas in the Real World</a><BR /> <a href="http://www.facebook.com/335047696629867">A study of the problems in teaching the slide rule</a><BR /> </div>