Article History
First Online: 28 September 2019
Compliance with Ethical Standards
: The study was approved by the appropriate institutional research ethics committee and has been performed in accordance with the ethical standards of the Declaration of Helsinki. Informed consent was obtained from all individual participants included in the study.
: This study received no funding.
: No potential conflict of interest was reported by the authors, Ivan Sever, Miroslav Verbič and Eva Klarić Sever.