Text and Data Mining valid from 2019-04-11
Received: 29 November 2018
Accepted: 25 March 2019
First Online: 11 April 2019
Ethics approval and consent to participate
: The study protocols of the NSPGDC were approved by the Ethics Committee of the Capital Institute of Pediatrics (SHERLL2015009). Informed consent was verbal and the ethics committee approved this procedure. Purpose, procedure, discomfort and benefit of the surveys were adequately explained by the staff of the cooperating groups to the parents, guardians and teachers involved in the survey. All participants were voluntary.
: Not applicable.
: The authors declare that they have no competing interests.
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