Text and Data Mining valid from 2018-05-25
First Online: 25 May 2018
Compliance with Ethical Standards
: The authors declare that they have no conflict of interest.
: All procedures performed in this study were in accordance with the ethical standards of the institutional committee and with the 1964 Helsinki Declaration and its latter amendments or comparable ethical standards.
: Informed consent was obtained from the parents of the children included in the study.