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Article History

Received: 7 June 2018

Accepted: 12 November 2018

First Online: 27 November 2018

Ethics approval and consent to participate

: The study was performed according to the Declaration of Helsinki and with the approval of the ethics committee Palermo 2 (number 87/2017). Informed written consent was obtained from the parents and/or legal guardian after receiving information about the study.

: Not applicable.

: The authors declare that they have no competing interests.

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