==Broken link to caburn at 20150106== 
 The reference number 2, to  http://www.caburn.com/resources/downloads/pdfs/sec1.2.pdf is broken today, with server unreachable. 
 It  can be found at http://www.caburn.co.uk/resources/downloads/pdfs/sec1.2.pdf. 
 Have not edited yet, in case it comes back...