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  Back Focus is the Society magazine published 4 times per year. Each issue is typically 28-40 pages and circulation is limited to members of the Society by mail. Articles are by members with specialist interests, and reflect exceptional levels of research.
 
 
 

A full version of this article by member Roger Burrows from Back Focus #104 can be downloaded as a PDF by clicking here.... (If necessary a copy of Adobe Reader can be downloaded from http://get.adobe.com/reader)