Funding for this research was provided by:
Deutsche Forschungsgemeinschaft (TU 89/13-1, MA 5039/3-1, FOR 2397)
Text and Data Mining valid from 2019-05-07
Received: 21 December 2018
Accepted: 26 April 2019
First Online: 7 May 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.