Text and Data Mining valid from 2018-09-10
First Online: 10 September 2018
Compliance with Ethical Standards
: There was no funding for this research.
: All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from parents of all individual participants included in the study.
: All authors declare no conflicts of interest.