Article History
Received: 21 August 2018
Accepted: 10 January 2019
First Online: 6 February 2019
Compliance with ethical guidelines
:
: J. Weber, P. Angerer and A. Müller declare that they have no competing interests.
: This article does not contain any studies with human participants or animals performed by any of the authors.
: The supplement containing this article is not sponsored by industry.