Received: 2 June 2017
Accepted: 20 March 2018
First Online: 2 April 2018
Ethics approval and consent to participate
: Approval for this study was given by the ethics committee of the Medical Faculty of Erlangen-Nuremberg University (registration number 227_14B). By voluntarily returning the questionnaire, the participants consented to the anonymous use of their data.
: Not applicable.
: The authors declare that they have no competing interests.
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