Funding for this research was provided by:
Bundesministerium für Bildung und Forschung (e:TOP 031A267B, e:TOP 031A267C, e:TOP 031A267A)
Text and Data Mining valid from 2019-06-28
Received: 26 April 2019
Accepted: 17 June 2019
First Online: 28 June 2019
Compliance with ethical standards
: The authors declare to have no conflict of interest.