- Correspondence to Dr Diane Gray, Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital, Klipfontein Road, Cape Town 7700, South Africa;
- Received 7 June 2015
- Revised 13 October 2016
- Accepted 17 October 2016
- Published in print 1 May 2017.
- Published online 10 April 2017.
- Published first 17 November 2016.
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