Article History
Received: 30 August 2018
First Online: 19 August 2019
Compliance with ethical standards
:
: Basil Hatz, Herman Frima and Christoph Sommer declare that they have no conflict of interest.
: All the procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.