Text and Data Mining valid from 2019-08-29
Received: 22 October 2018
Accepted: 22 August 2019
First Online: 29 August 2019
Ethics approval and consent to participate
: National Ethics Committees approved the study protocol and informed consent was obtained from the students, parents and/or school officials (Center for Disease Control, 2017).
: Not applicable.
: The author declares no competing interests.