Text and Data Mining valid from 2019-01-11
Received: 3 September 2018
Accepted: 3 January 2019
First Online: 11 January 2019
Ethics approval and consent to participate
: All the participants (legal guardians) have filled informed consent forms which were approved by the ethic committee of Mashhad University of Medical Sciences.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.