Funding for this research was provided by:
Convenio de Desempeño Regional, FRO 1301 (UNT15-0012)
Text and Data Mining valid from 2018-12-01
Received: 26 April 2018
Accepted: 28 November 2018
First Online: 16 December 2018
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee of the Universidad de La Frontera, Temuco, Chile with resolution number 061/2015. Informed consent from all parents and verbal assent from children was obtained to consider their participation in the study.
: Not applicable.
: The authors declare that they have no competing interests.
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