John, Stefan
Article History
Received: 4 November 2019
Accepted: 14 January 2020
First Online: 12 February 2020
Compliance with ethical guidelines
:
: S. John declares that he has no competing interests.
: For this article no studies with human participants or animals were performed by the author. All studies performed were in accordance with the ethical standards indicated in each case.
: The supplement containing this article is not sponsored by industry.
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