http://public.eblib.com/EBLPublic/PublicView.do?ptiID=616064
http://www.netlibrary.com/urlapi.asp?action=summary&v=1&bookid=346200
http://whqlibdoc.who.int/publications/2010/9789241564038_eng.pdf
http://site.ebrary.com/id/10430899
http://www.myilibrary.com?id=289745&ref=toc
http://www.myilibrary.com?id=289745
http://www.netlibrary.com/urlapi.asp?action=summary&v=1&bookid=346200
http://whqlibdoc.who.int/publications/2010/9789241564038_eng.pdf
http://site.ebrary.com/id/10430899
http://www.myilibrary.com?id=289745&ref=toc
http://www.myilibrary.com?id=289745