Schaefer, Michael
Article History
Received: 25 April 2017
Accepted: 22 October 2017
First Online: 7 November 2017
Compliance with ethical standards
:
: Author MS declares that he has no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee (DGPs) and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual participants included in the study.