Text and Data Mining valid from 2019-07-18
Received: 18 April 2019
Accepted: 1 July 2019
First Online: 18 July 2019
Ethics approval and consent to participate
: The surveys were conducted in accordance with the ethical principles of the Declaration of Helsinki. Verbal informed consent was obtained from each participant’s parent or guardian after providing complete information about the study. The study design was approved by the Ethical Committee Board of the University of Sassari (Italy) in 2011 and then reapproved in 2016. (ExternalRef removed.
: The authors declare that they have no competing interests.