Text and Data Mining valid from 2018-11-26
Received: 9 October 2017
Accepted: 2 November 2018
First Online: 26 November 2018
Ethics approval and consent to participate
: All participants and their respective guardians gave written consent to participate in the study. This study has been approved 19/12 2011 by the regional review board in Stockholm (Dnr 2011/1593–31/5).
: Not applicable.
: The authors declare that they have no competing interests.
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