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Article History

Received: 30 May 2018

Accepted: 1 May 2019

First Online: 10 May 2019

Ethics approval and consent to participate

: The study was approved by the Danish Data Protection Agency (no. 1–16–02-461-16). No consent was obtained from a parent or guardian on behalf of any participants. It was voluntary for the adolescents to answer the questionnaire, and they had the right to withdraw their undertaking of participation at any time. All the answers were treated strictly confidential, and the adolescents were guaranteed full anonymity. All procedures followed were in accordance with the ethical standards of the Helsinki Declaration of 1975, as revised in 2000.

: Not applicable.

: The authors declare that they have no competing interests.

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